Despite pressure and threats of sanctions on the two rebel groups that have rejected the pact, AU officials said no such overtures had been made.
At the same time, they said the pan-African body might be willing to accept signatures to the May 5 agreement on Thursday, considering logistical problems would-be signers may have had in meeting the May 31 deadline.
"No one has called to say they will sign but they know how to reach us," a senior AU official said at the bloc's headquarters in Addis Ababa after the 2100 GMT deadline passed.
"We'll see what happens [on Thursday] morning and consider it."
Noureddine Mezni, a spokesman for the AU Mission in Sudan (Amis), said in Khartoum that Alpha Oumar Konare, the AU commission chief, would on Thursday "indicate the next steps to be taken".
The groups holding out have refused to sign the accord aimed at ending three years of conflict in the Darfur region of western Sudan, which has left some 300,000 people dead and 2.4 million homeless.
The conflict has killed about
While the main wing of the region's Sudan Liberation Movement (SLM) did sign the AU-brokered deal, a splinter faction and the Justice and Equality Movement (JEM) have refused, saying it fails to address their concerns.
Shortly before the deadline expired, Mezni said efforts were still under way by Salva Kiir, the southern Sudan former rebel chief, now Sudanese first vice-president, to persuade those who did not sign the pact to do so.
A source close to the negotiations said Kiir had received a delegation led by Konare's Sudan envoy, Baba Gana Kingibe, and that he would himself soon host talks between the AU and holdout rebels in the south of the country.
On Wednesday, AU officials in Addis Ababa said a group claiming to represent a JEM splinter faction had arrived there to meet officials hours before the deadline.
"We have been approached by a certain number of groups who are favourable to the DPA," AU Peace and Security Council commissioner Said Djinnit told reporters, referring to the Darfur Peace Agreement.
Diplomats in the Ethiopian capital said the alleged JEM dissidents were prepared to sign the deal even after a spokesman for the group said it could not agree unless substantial changes were made.
"We are finalising a different document, a mechanism will be put in place to receive the signatures of groups and individuals who have chosen the path of peace"
AU Mission in Sudan spokesman
Mezni said AU officials were drawing up a new document that would allow dissident factions and commanders to escape sanctions.
"We are finalising a different document, a mechanism will be put in place to receive the signatures of groups and individuals who have chosen the path of peace," he said.
A source close to the AU said seven field commanders from Abdel Wahid Mohammed al-Nur's holdout SLM faction had arrived in Addis Ababa to join the peace process "and before that many others did the same".
Al-Nur himself has said he will not sign unless Khartoum agrees to pay compensation and give his SLM wing a greater security role and a say in local and federal government.
Officials involved in the peace effort have warned al-Nur that he risks becoming "irrelevant" if he does not sign, but his group's absence from the accord will likely plunge Darfur into further violence.