ABUJA, Nigeria — Sudanese leader Omar al-Bashir has left Nigeria, the spokesman at his embassy said Tuesday, following demands from human rights activists for his arrest over charges of genocide and war crimes in Darfur.

Spokesman Mohammed Moiz said al-Bashir left to fulfill another engagement. Moiz said he left Abuja, Nigeria's capital, at 3 p.m. Monday, less than 24 hours after he arrived and in the middle of a two-day summit ending Tuesday.

Nigeria's Vanguard newspaper reported that the Sudanese leader was expected to make a presentation Monday afternoon at an African Union summit but failed to show up.

"Business as usual is over for this head of state suspected of the most serious crimes committed in Darfur," said Elise Keppler of New York-based Human Rights Watch. "Al-Bashir faced intense pressure for his arrest from local activists when he tried to visit Nigeria, including court action."

Rights lawyers filed a suit in the Federal High Court on Monday to try to compel Nigeria's government to arrest al-Bashir. And a civil rights group urgently appealed to the International Criminal Court to refer the government to the United Nations Security Council for allowing the visit.

Presidential spokesman Reuben Abati told The Associated Press that al-Bashir had come to attend the African Union summit, and not at Nigeria's invitation. He said Nigeria allowed him to come in line with instructions from the African Union, which has told its 53 member states not to cooperate with the European-based court that some accuse of targeting Africans.

The International Criminal Court said it demanded Monday that Nigeria "immediately arrest" the fugitive. It noted that it could refer the Nigerian government to the United Nations Security Council for failing to execute an order of the court, of which it is a member.

A statement Tuesday recalled that the court has issued two arrest warrants for al-Bashir, in 2009 and 2010, to stand trial for five counts of crimes against humanity, two counts of war crimes and three counts of genocide against the Fur, Masalit and Zagawa tribes in Darfur.

The violence continues in Darfur, where black tribes are battling soldiers loyal to al-Bashir's Arab-led government in Khartoum.

On Tuesday, European Union High Representative Catherine Ashton urged Nigeria "to respect its obligations under international law to arrest and surrender those subject to an arrest warrant from the ICC."

The United States Embassy said it regrets Nigeria's decision to welcome an indicted criminal. Former colonizer Britain expressed its "disappointment."

The furor around al-Bashir's presence totally eclipsed the conference, which is looking for ways to fight communicable diseases like AIDS, tuberculosis and malaria.

A statement after the conference ended Tuesday devoted more space to al-Bashir than the health issues, saying Nigeria's welcome of al-Bashir complied with its obligations as a member state of the African Union.

"Any attempt to make an issue out of the attendance of President El- Bashir at the AU Summit will only serve to unnecessarily shift focus away from the important objectives of the Special Summit," it said. "It is therefore a matter between the African Union and the international community."

Leaders from eight other African countries are attending the summit, including Kenya, which has shunned al-Bashir.

On Tuesday, a group of human rights activists gathered outside the government secretariat carrying signs saying "Not to al-Bashir, No to impunity" and "Nigeria not a safe haven for war criminals."

South Africa, Malawi, Uganda, Kenya, Zambia, and Central Africa Republic "have specifically made clear Bashir will be arrested on their territory, seen to it that other Sudanese officials visit instead of Bashir, relocated conferences or otherwise avoided his visits," according to human rights lawyer Chino Obiagwu, who head the Nigerian Coalition on the ICC.

Al-Bashir has visited several African countries since the warrants against him were issued, including Chad, Djibouti and Malawi.

The 69-year-old leader seized power in a bloodless coup in 1989.