Despite intense pressure and threats of sanctions on two rebel groups that have so far rejected the pact and signs that dissident factions might sign on at the last minute, AU officials said no such overtures had been made.
At the same time, they said the pan-African body might still be willing to accept signatures to the May 5 agreement because of 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," said a senior AU official at the bloc's headquarters in Addis Ababa after the deadline passed.
"We'll see what happens (Thursday) morning and consider it."
Noureddine Mezni, a spokesman for the AU Mission in Sudan said in Khartoum that AU commission chief, Alpha Oumar Konare Konare, would "indicate the next steps to be taken".
The holdout groups have refused to sign the accord aimed at ending three years of conflict in Darfur, which has left some 300,000 people dead and 2.4 million homeless.
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, Mr Mezni said efforts were still under way by southern Sudan ex-rebel chief, now Sudanese First Vice President, Salva Kiir to "persuade those who did not sign" the pact to do so.
A source close to the negotiations said Mr 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.