ABIDJAN, Ivory Coast - West African leaders who delivered an ultimatum to Laurent Gbagbo to step down or face a military ouster left Ivory Coast late Tuesday without taking him into exile a month after the United Nations said he lost the disputed presidential election.

In a sign of escalating tensions in the country, the U.N. mission said that one of its peacekeepers had been wounded with a machete when a large crowd in a pro-Gbagbo neighborhood encircled a convoy and set one of its three vehicles on fire.

The regional delegation led by presidents from Sierra Leone, Cape Verde, and Benin held meetings with both Gbagbo and the internationally recognized election winner, Alassane Ouattara, then returned to meet with Gbagbo a second time before leaving the country.

Gbagbo, who has been in power for a decade in Ivory Coast, has shown no interest in stepping aside despite the calls for him to go. While Ouattara has been endorsed by most of the world, Gbagbo still maintains control of Ivory Coast's military and security forces.

Weeks of postelection violence have left at least 173 people dead, according to the United Nations. The toll is believed to be much higher: The United Nations said it has been unable to investigate reports of a mass grave because of restrictions on U.N. personnel movements.

Concerns have also grown about violence targeting peacekeepers since Gbagbo called for the U.N. mission, known as UNOCI, to leave earlier this month, and the United Nations said Tuesday that one of its peacekeepers had been wounded.

"UNOCI vigorously condemns this attack and reiterates its determination to pursue its work in the service of the Ivorian people," the U.N. mission said in a statement.

The regional leaders had hoped to persuade Gbagbo to leave Ivory Coast with them after the one-day mission, saying he would be offered asylum in neighboring countries.

The 15-nation regional bloc ECOWAS threatened to use "legitimate force" if Gbagbo did not relinquish power. Nigeria has the strongest army in the region and is expected to play a major role if an operation is undertaken to oust Gbagbo.

State Department spokesman Mark Toner commended ECOWAS' leadership and said the United States was prepared "to take even stronger actions," such as sanctions, "as needed."