By Will Ross
BBC News, Abuja
Wole Soyinka says critical issues have ground to a halt
After weeks of rumours and reports that Nigerian President Umaru Yar'Adua had died or was brain damaged, a BBC interview with the ailing leader broadcast on Tuesday will come as a relief to many.
But the perception that the political crisis is not over is widespread.
And the interview did not stop several hundred people from gathering for a march organised by a recently formed organisation known as Save Nigeria Group.
"Arise Nigeria. It is time to take charge of our destiny," one protester shouted on the wide, clean streets of the capital Abuja.
Placards read "Umaru Where Are You?" and "Enough Is Enough" - a reference to the prolonged absence of Mr Yar'Adua.
Diet of rumour
Accompanied by a brass band but still in need of an inspirational singer from the Fela Ransome Kuti mould, the marchers headed to the National Assembly.
For them, the unease created by the president's absence was not altered by his interview on the BBC.
"I heard the president this morning. But that is not what we are looking for. We want to see the president on a live telecast on the sickbed," said one protester.
"We are not thinking of the voice - the voice is deception."
There are many Nigerians who, having been fed a diet of rumour for several weeks, doubt the authenticity of the interview.
Leading the marchers was the Nobel prize winner Wole Soyinka - his shock of white hair clearly visible in the crowd.
He says the issue is not just about whether the president is present or not but whether the government is working well.
"Serious critical issues, like electoral reforms, for instance, constitutional reform etc. These have ground to a halt," he said.
"And this has been kept deliberately so because there is a small cabal which profits by the hiatus in control, in government, in supervision."
He suggested corruption was booming and worried that efforts to pacify the oil rich Niger Delta were being threatened by the president's absence.
"It doesn't matter if President Yar'Adua walks here on his two legs today. We will cheer him as a fellow human being who has recovered from a very trying illness. But at the same time we'll challenge him," he said.
For the past 50 days the government has remained tight lipped on the president's health. The official line has been that he is getting better but no details or proof were ever given.
Analysts suggest the information vacuum is being prolonged on purpose - whilst a small elite makes plans ahead of next year's elections.
Many Nigerians doubt the authenticity of the president's radio interview
The question now is whether there will be a snowball effect and the calls for the president to step down will grow.
Tuesday's march was peaceful and relatively small.
The fact that the police allowed the demonstration to go ahead - not a given in so many countries in Africa - may inspire more people to join in the other marches which will inevitably follow.
There is also pressure from the courts. On Thursday several cases are due to continue.
The Nigeria Bar Association maintains that according to article 145 of the constitution, the president was compelled to hand over power when he was taken ill and left the country.
However, the president's allies say this section of the law does not compel him to hand over but lays out what he needs to do if he chooses to hand over.
The National Assembly has now voted to send a delegation to Saudi Arabia to meet President Yar'Adua and his health is due to be discussed.
However, Nigerians maintain they have not always been told the truth about the president's health.
So there are plenty of Nigerians who would be more than willing to lend the senators a video camera to get a real picture of how their president is doing.