The UN Secretary-General Kofi Annan has said the Sudanese government has made no progress in stopping attacks on civilians and has not punished those behind atrocities in its western Darfur region.
The government has also not made progress in pinning down a ceasefire, as required by UN Security Council resolutions, Mr Annan said in his second monthly report to the 15-nation council on Darfur, the site of what UN officials say is the world's worst humanitarian crisis.
Reining in marauding Janjaweed militias, ending attacks on civilians and prosecuting those behind such attacks "are key for progress towards full security" in the region, he said.
Yet "in these areas no further progress was made during the month of September," he said in the report.
"Today, still increasing numbers of the population of Darfur are exposed, without any protection from the government, to hunger, fear and violence," Mr Annan said on Monday. "It goes without saying that implementing Security Council resolutions is obligatory."
Darfur has been torn by violence since rebels took up arms against the Khartoum government in February 2003, saying it had neglected and marginalised the impoverished region.
The rebels accuse the government of arming mounted Arab militias, known as Janjaweed, to loot and burn non-Arab villages in a campaign of ethnic cleansing. Arab nomads and mostly non-Arab farmers have fought over resources for years in arid Darfur.
Since the rebellion started last year, more than 1.5 million people have been driven from their homes and up to 50,000 killed by violence, hunger or disease, the United Nations says.