Beijing residents woke up the other morning to find their cars caked in mud, the result of the first fall of dusty rain after the arid winter, an event which usually heralds the arrival of spring.

But the Beijing spring which everyone is suddenly talking about here is concerned with the political climate rather than the weather. Long-time observers speak of a developing social climate reminiscent of a decade ago, before the crackdown on pro-democracy students in Tiananmen Square in June 1989.

They point to a livelier press, a growing openness among academics, writers, journalists and party officials, and the increasing frequency of street demonstrations over issues like unemployment and housing.

Some detect a loosening of rigid political controls. "There is definitely a more relaxed atmosphere," said one Beijing intellectual as we sipped coffee at a pavement cafe, "but it is very cautious so far. Almost everyone is politically very apathetic and the dissident movement is tiny."

He admitted, however, that just two days ago he had been startled to hear a professor on CCTV, the Central Chinese television service, calling for political reform, something he had not heard for 10 years on the officially-controlled media. The staid newspapers have also become more dynamic recently with an outbreak of muck-raking over corruption among police and party officials.

There is also a new environmental glasnost in the press which a month ago began to publish a pollution index. Yesterday the English-language China Daily said Beijing "has been so polluted by coal combustion and auto emission" that the sky is rarely seen.

In the universities, a few well-connected academics have been publicly calling for more openness and democracy without getting arrested, mainly because they do not challenge the overall authority of the Communist party.

Two weeks ago Prof Shen Baoxing, of the Central Communist Party School told the Economic Times: "Only in a democratic environment can people dare to voice new opinions, and their intelligence, wisdom and ability be fully brought into play. If we don't encourage people to think freely, and voice new opinions, our society will actually be stagnant, though it may seem tranquil."

This recalls Mao Zedong's famous 1950s dictum: "Let 100 flowers blossom and 100 schools of thought contend." People took him at his word and later were punished for dissent. Now, previously forbidden ideas are tentatively blooming again.

The vice-president of the Communist Party School, Mr Xing Bensi, said a plan to streamline the government bureaucracy announced at the recent People's Congress had paved the way for political reform and that China aimed to build a democratic socialist country ruled by law and incorporating the best of Western-style democracy.

China has certainly become more receptive to foreign ideas. A group of four Irish High Court judges who visited China this month concluded the authorities were serious about law reform.

Economic reforms are causing considerable pain and the government may feel that a safety-valve is needed. In many cities, demonstrations against unemployment are common and the police are handling them carefully.

I came across one protest by old people in the northern industrial city of Shenyang in February. They sat on little chairs blocking Peace Avenue in protest at not receiving their pensions from bankrupt enterprises. People said they were also acting as surrogates for laid-off workers.

Even in Beijing, where open dissent is forbidden, people are becoming bolder. On Wednesday of last week dozens of residents staged a public protest outside Beijing city offices, near Tiananmen Square, over plans to demolish their homes to make way for an underground line. Police eventually persuaded them to leave in a bus provided by the authorities.

The change in the political climate has coincided with the decline of the unpopular hard-liner Mr Li Peng, who stepped down as Premier last month in favour of Mr Zhu Rongji, who is more open to liberal reform. Mr Zhu was repressed himself 40 years ago when he accepted Mao's invitation to speak freely, and he has brought a new openness to the Chinese government.

Some observers are comparing the dynamic new Premier to Party Secretary Zhao Ziyang, who in the late 1980s became a hero abroad for starting a programme of radical reform to restructure the urban economy and revitalise state-owned enterprises. Mr Zhao is still under house arrest after his reforms ignited the protests which led to the Tiananmen Square crackdown.

In the Zhao era reformers were given licence to openly attack leftists, something which is also happening now. A new book called Confrontation has been given wide play in the press. It is a reply to four factional party documents which attack the reforms for sharpening class contradictions, stirring up social tensions, and corroding the ideological pillar of party and state.

But while the book accuses leftists of trying to sabotage reforms, it stops short of calling for fundamental change. Prof Shang Dewen, of Beijing University, who has called on President Jiang to abandon the "dictatorship of the proletariat" and gradually introduce democracy along Western lines, said he had been unable to get his pro-reform book published.

The debate represents the small swings of a pendulum, Prof Shang said. "You often find such tight-loose-tight cycles in history. Such small changes never last, though, without fundamental change to the system."

The new openness has resulted not just from the course of internal debate but from a series of foreign policy initiatives which China is unlikely to reverse. Beijing has managed to end ritual international condemnations of its human rights record by entering into a dialogue with the EU, the US and other countries, and this has produced a dynamism of its own.

In the run-up to a visit by UN Human Rights Commissioner, Mrs Mary Robinson, in September, Beijing has promised to sign the UN International Covenant on Civil and Political Rights.

Another important factor is the planned visit by President Clinton in June, which China regards as a diplomatic coup. To help achieve its objective of normal relations with the world's superpower, China released a dissident, Mr Wei Jingsheng, just before President Jiang visited Washington last year, and there are persistent rumours now that it will free Mr Wang Dan, the leader of the Tiananmen Square students, before Mr Clinton arrives.

Many dissidents still languish in prison, however, and conditions can be harsh. Mr Wang Dan's parents complained last week that he was being denied medical treatment. Indeed, some observers believe that there is only token openness.

Mr Xu Wenli, a leading member of the 1978-79 Democracy Wall movement, who was detained overnight two weeks ago after calling for the creation of a human rights watchdog group, said the Chinese government did not want to behave too harshly towards dissidents because this would only embarrass the US side. Police who confiscated his computer warned him not to "cross the line" or publish any material without first seeking approval.

Other outspoken activists have been detained in different parts of China. The Hong Kong-based Information Centre for Democracy and Human Rights said a dissident, Mr Shen Liangqing, was sentenced to two years of reform through labour for contacting human rights groups.

In February a Chinese court gave a three-year labour camp sentence to a Shanghai dissident, Mr Yang Qinheng, for "disturbing public order", allegedly because of a letter he wrote to parliament about unemployment.

A new Beijing spring may be in the offing, but it is still risky for Chinese citizens to speak out unless they are well-connected members of the party elite, and do not cross the line by demanding the immediate downfall of the system.