ABUJA — Ailing Nigerian President Umaru Yar'Adua broke a seven-week silence and told the BBC he hopes to leave a Saudi hospital and resume his duties, as thousands rallied on Tuesday to demand he step down.

The 58-year-old president's condition has been the source of widespread speculation in Nigeria, and some online publications reported on Monday that he had died the previous day.

Thousands of Nigerian opposition supporters staged a protest rally in the capital Abuja early Tuesday to demand he relinquish power to his deputy.

But speaking by telephone to the BBC, Yar'Adua said he is recovering.

"At the moment I am undergoing treatment, and I'm getting better from the treatment. I hope that very soon there will be tremendous progress, which will allow me to get back home," the BBC quoted him as saying.

"As soon as my doctors discharge me, I will return to Nigeria to resume my duties.

But critics contend that his being alive, but absent, changes little in the power vacuum in the country.

Yar'Adua did not delegate executive powers to Vice President Goodluck Jonathan when he left. The law demands that he do so in writing.

A spokesman for the main opposition, Action Congress, said the group is happy that the head of state is alive but expressed disappointment that he chose a foreign media outlet to speak to his country, which has been on edge for weeks.

" It's quite shameful and a very big disrespect to Nigerians," Action Congress spokesman Lai Mohamed told AFP. "He has contempt for the local media and no respect for many Nigerians, many of whom have no access to the BBC."

Thousands of opposition and rights activists, led by Nobel laureate Wole Soyinka, gathered Tuesday for the start of protests in the administrative capital Abuja as lawmakers were to meet to discuss the political vacuum Yar'Adua's absence created.

Sporting white vests emblazoned with the words "enough is enough," the protestors brandished placards demanding "Yar'Adua speak to us" and "What's happening to Yar'Adua — We want to know."

On what impact the telephone interview would have on concerns over a power vacuum in Africa's most populous country and second largest oil exporter, Mohamed said: "It changes very little".

"The fact that he is alive does not say anything about his state of health," said Mohamed.

Yar'Adua's voice sounded weak in the interview, the BBC said.

The president had not been seen or heard from since he was flown to hospital in Saudi Arabia on Nov. 23 to be treated for acute pericarditis, an inflammation of the membrane around the heart.

Critics complain that his long absence has stalled government business, and calls are increasing for the president to step down.

The rally, to be addressed by Soyinka and former Biafra warlord Chukwuemeka Odumegwu-Ojukwu, is being organized to demand an end to the stasis, vacillation over electoral reform, and widespread corruption, as well as Nigeria's being put on a U.S. terror watch list.

Washington established the watch list after the failed attempt of a 23-year-old Nigerian, Umar Farouk Abdulmutallab, to blow up a U.S. airliner on Christmas Day.

The interview with the BBC was published hours after the president's spokesman, Olusegun Adeniyi, moved to dismiss mounting rumors over his state of health.

Yar'Adua expressed his gratitude for his nation's prayers for his recovery.

"I wish, at this stage, to thank all Nigerians for their prayers for my good health, and for their prayers for the nation."

Influential regional governors from Nigeria's 36 states met for several hours late Monday to early Tuesday but made no statement on Yar'Adua.

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