Nigeria's National Assembly has empowered vice president Goodluck Jonathan to take over for the ill and absent president of oil-rich Nigeria, Africa's most populous country.

Both the House of Representatives and the Senate passed measures calling on Jonathan to take over for President Umaru Yar'Adua until he returns from Saudi Arabia, where he as been receiving medical treatment for a heart condition since late November.

Yar'Adua's absence has caused a cease-fire with militants in the oil-rich delta to unravel and had left no one formally in charge of the nation of 150 million.

Yar'Adua has suffered from kidney problems and an inflammation of the sac surrounding the heart.

Lawsuits and protesters have called on him to cede power.