Nigeria's president, who has not been seen since going into hospital in Saudi Arabia for heart treatment in November, has told the BBC he is recovering.

自去年11月就被送往沙特阿拉伯治疗心脏病的尼日利亚总统近日接受BBC采访时称，自己正处于康复之中。

President Umaru Yar'Adua has been abroad for weeks  

In his first interview since then, Umaru Yar'Adua said he hoped to make "tremendous progress" and to return to Nigeria to resume his duties.

Nigerian opposition¹ parties have been demanding evidence about the true state of Mr Yar'Adua's health.

A rally集会 has been called for Tuesday, mainly to protest over his absence.

There are three different court cases under way calling for power to be transferred to the Vice-President, Goodluck Jonathan.

Mr Yar'Adua is also known to have kidney肾脏 problems.

'Save Nigeria'

Speaking by telephone, Mr Yar'Adua said he was making a good recovery.

"At the moment I am undergoing经受，经历 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," he said.

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

Rumours² had been rife流行的，普遍的 that he was critically ill and unable to return to the presidency⁴.

Under the banner Enough Is Enough, an organisation⁵ called the Save Nigeria Group called people on to the streets of the capital, Abuja.

There is a perceived感知到的 danger of a power vacuum真空 in a country which only saw the back of military rule just over 10 years ago, the BBC's Will Ross reports from the city.

The opposition plan is to march to the national assembly where senators are expected to be discussing the president's health.

Prominent opposition politicians and lawyers, Nobel laureate Wole Soyinka and the Biafran secessionist leader, Chief Emeka Ojukwu, will be among the demonstrators.

It is not clear if the demonstration⁶ will be well attended, our correspondent says.

Nigerians may be worried about their absent president but whether they will take time off to demonstrate is another matter, he adds.