The declaration came after Annan urged the UN Security Council to take immediate steps to stop the Darfur war, which has killed at least 70,000 people and displaced 2 million.
"The Abuja process is thus relaunched as both sides have made firm commitments," the Chadian mediator, who declined to be named, said at the talks, due to end later on Thursday.
The agreement was reached between Sudanese government officials and Darfur's two main rebel groups - the Sudan Liberation Movement and the Justice and Equality Movement.
Nigeria's President Olusegun Obasanjo, current chair of the 53-member African Union, said on Wednesday he hoped peace talks would start again in Abuja at the end of February.
"Darfur's people are living in hell," Chad's President Idriss Deby told the talks, also attended by international mediators and AU Commission Chairman Alpha Oumar Konare.
In New York, Annan backed a call by the Bush administration for a travel and assets freeze on those violating a cease-fire in Darfur, a western region of Sudan where rebels have fought since 2003 against government forces and militias.
Annan said the UN Security Council should consider a full range of options - targeted sanctions, stronger peacekeeping efforts, new measures to protect civilians and pressure on all sides for a lasting political solution in the western region.
"While the United Nations may not be able to take humanity to heaven, it must act to save humanity from hell," Annan said at a meeting on Wednesday to review a report by a UN-appointed commission on Darfur.
The report accused the Sudanese government and militias of "heinous crimes". It said rebels were responsible for serious crimes but its chief criticism was directed at the government's inability to stop marauding Arab militiamen.
"The report demonstrates beyond all doubt that the last two years have been little short of hell on earth for our fellow human beings in Darfur," Annan said.
After years of tribal conflict over scarce resources, Darfur's rebels took up arms in February 2003, accusing Khartoum of neglect and giving preferential treatment to Arab tribes.
They say the government mobilised Arab militias, known as Janjaweed, to loot and burn non-Arab villages. The government says it recruited militias to fight the rebellion but not the Janjaweed, whom it has called outlaws.
The leaders of Sudan and Chad on Wednesday warned the international community not to send non-African troops to Darfur or to impose sanctions. The AU has 1,400 troops in Darfur and expects the force to grow to more than 3,000.
Many see it as ill-equipped to stem the killings, prompting some talk of sending in peacekeeping troops from outside Africa.