Darfur: International observers are investigating reports that Sudanese government aircraft bombed a town in Darfur, in what would be the most serious breach of a shaky ceasefire in the region this year.
African Union monitors said 100 people died in the attack on Wednesday night but declined to blame either side in the two-year conflict.
Other sources said Russian-made Antonov planes - used only by the government - attacked targets around Al-Malam on the border between North and South Darfur.
Earlier this week, human rights groups said that more than 100 people were killed in a second incident, when the village of Hamadab was destroyed.
The United Nations has confirmed that 9,000 people fled their homes, but has not identified the group behind that attack.
The area around Al-Malam has been the scene of intense fighting in the past few days. The government accused rebels of burning eight villages and killing dozens of people.
Yesterday, an aid agency source told Reuters that the government had taken revenge.
"The planes were flying very low just south of El-Fasher and then the explosions were heard from that direction. It was near the al-Malam area," said the source.
African Union observers, responsible for monitoring the ceasefire signed in April last year, are investigating the incident.
Mr Adam Thiam, a spokesman at the AU headquarters in Addis Ababa, said: "The AU office in Khartoum has confirmed that the attack took place on Wednesday night."
He declined to say who was responsible for what he called the "bombardment".
However, he noted that similar attacks had been launched by the Sudanese government side in the past.
There have been more than 100 violations of the ceasefire since late last year.
January began with optimism that peaceful solutions would be found for several conflicts in Sudan.
The government and southern rebels signed a peace agreement ending a 21-year civil war in the south of the country.
It was seen as the first step towards a federal government structure which might allow greater autonomy for Darfur and coax the rebels into laying down their arms.
However, several human rights groups warned that the government might use the deal in the south as an opportunity to redeploy troops in Darfur.
Meanwhile a UN investigation into whether crimes committed in the region amount to genocide has been submitted to the UN Secretary General Mr Kofi Annan.
It is expected to be made public next week.