State governors from volatile southern Nigeria have asked President Umaru Yar'Adua to free a jailed militant leader.

The three governors say the militant, Mujahid Dokubo-Asari, should be released on the grounds that his health is poor.

Dokubo-Asari is the leader of the Niger Delta People's Volunteer Force. The group is one of several in the Niger Delta demanding that locals get more of the region's vast oil wealth.

Dokubo-Asari has been on trial for treason charges since 2005. Several Niger Delta militant groups have demanded his release.

The governors from the states of Bayelsa, Rivers and Delta made their request during a meeting with the president in Abuja late Monday.

The Niger Delta is the site of frequent attacks on oil facilities and even more frequent kidnappings of foreign workers. Some actions are the work of criminal gangs, while others are carried out by the militant groups.

On Saturday, the most prominent group, the Movement to Emancipate the Niger Delta, promised to stop attacking oil facilities for one month. The group called its moratorium an "olive branch" toward President Yar'Adua, who was inaugurated last week.

Nigeria is Africa's largest oil producer but output has been down about 25 percent since last February because of the kidnappings and attacks on oil facilities.

Some information for this report was provided by AFP and Reuters.