Russian president Vladimir Putin pledged moral support and new loans for Moscow's ex-Soviet ally Belarus in his first foreign visit yesterday since taking office.
The European Union has tightened sanctions against Belarus and withdrew ambassadors from Minsk in February over human rights violations.
Relations improved after jailed opposition leader Andrei Sannikov was released.
"Russia and Belarus will coordinate efforts to counter attempts to interfere in the internal affairs of the Union State and apply pressure through the introduction of restrictive measures or sanctions," Mr Putin and Belarus president Alexander Lukashenko said in a joint statement.
Russia and Belarus have formed a so-called Union State and are also, together with Kazakhstan, members of a common economic space, a plan for integration among ex-Soviet countries that Mr Putin has presented as one of his top priorities in office.
Mr Putin hosted the leaders of ex-Soviet states in the Kremlin a week after his inauguration but stayed away from a trip to the United States for a summit of the Group of Eight countries, sending prime minister Dmitry Medvedev instead.
In power since 1994,Mr Lukashenko has cracked down on opposition since winning a fourth term in office in 2010. The European Union has imposed sanctions such as travel bans against him and other officials.
Mr Putin, who returned to the Kremlin amid the biggest opposition protests of his 12-year leadership of Russia, chose Belarus as his first foreign destination. From Minsk he was due to travel to Berlin and Paris.
"Vladimir Vladimirovich, I am very grateful for this visit," Mr Lukashenko told Mr Putin outside his residence in the forest near Minsk as the Russian leader fought irritably with mosquitoes.
"This visit is more important for us than the economic agreements we have with Russia and other countries. It is a signal that we have a great future."
Mr Putin said that an anti-crisis fund mainly financed by Russia would give Belarus a third $440 million tranche of a loan programme that has helped it to avert economic collapse, stressing "the positive dynamics" in the Belarussian economy.
Belarus is due to receive $3 billion in loans between 2011 and 2013, and in return has pledged to sell $2.5 billion worth of state assets a year for three years.
A Belarus opposition group posted on its website pictures of an anti-Putin slogan which it said was hanging on a bridge over an airport highway as Mr Putin drove to the meeting.
Reuters