Nigeria cabinet told to rule on sick President Yar'Adua
President Umaru Yar'Adua has been absent from Nigeria for weeks
The Nigerian cabinet has been ordered by the federal court to decide within 14 days if ill President Umaru Yar'Adua is fit to lead the country.
The president has been in Saudi Arabia for two months, receiving treatment for a heart condition.
The court ruling directed the cabinet to pass a resolution about whether he "is incapable of discharging the functions of his office".
The president's absence has raised concerns about a power vacuum.
The Federal High Court ruled that cabinet should hear testimony from five doctors, one of whom should be the president's personal physician.
If cabinet decides that the president is not fit to carry out his duties, the vice-president would take over, the court ruled.
To say that I, Olusegun Obasanjo, deliberately picked somebody who is an invalid, is the height of insult
The court was responding to a law suit brought by opposition activist Farouk Adamu Aliyu.
He had asked for the judges to sack the president over his failing health and for failing to abide by the provisions of the constitution.
His lawyer Bamidele Aturu told the BBC that the judgement was a "victory for democracy".
On Thursday, Mr Yar'Adua's predecessor Olusegun Obasanjo urged the president to step down if he is not fit to continue.
"If you take up a job, elected... and then your health starts to fail you and you will not able to deliver, to satisfy yourself and satisfy the people you are supposed to serve, then there is a path of honour and path of morality," he said in his first comments on Mr Yar'Adua's health.
He denied that he had been irresponsible when choosing his successor, AFP news agency reports.
Sola Tayo, commentator on Nigerian issues: "There are lots of unsubstantiated rumours that his condition is a lot more serious"
"To say that I, Olusegun Obasanjo, deliberately picked somebody who is an invalid, is the height of insult," he said.
Mr Obasanjo handpicked Mr Yar'Adua to succeed him but the pair have since fallen out.
On Thursday, more than 1,000 people gathered in Lagos to protest against Mr Yar'Adua's prolonged absence.
Some carried placards saying: "Enough of the offshore president and a people's constitution now."
YAR'ADUA ILLNESS TIMELINE
23 November 2009: Goes to hospital in Saudi Arabia
26 November 2009: Presidential doctors say he has pericarditis - inflammation of the heart lining
23 December 2009: First court case filed called him to step down
30 December 2009: Chief justice sworn in. Lawyers say this is illegal in president's absence
5 January 2010: Two more court cases filed and a human rights group wants president declared "missing"
12 January 2010: President gives first interview since going to Saudi Arabia
The protesters argue that when the president left the country to go to hospital he did not hand executive powers to his deputy, as required by the constitution.
In the wake of his absence, the president has faced various legal challenges by Nigerians concerned by their leader's absence.
Last week one ruling said Vice-President Goodluck Jonathan could perform all presidential duties while Mr Yar'Adua was away.
Two other court cases are waiting to be heard.
The situation has been complicated by the custom in Nigeria's ruling People's Democratic Party to alternate power between north and south.
Mr Yar'Adua is a northerner, while Mr Jonathan is from the south.
Some northern power-brokers are believed to be loath for him to take over, as this would shorten the north's "turn" in power.
In a BBC interview from his hospital bed last week, the president said he was recovering and hoped to return home, without giving a timeframe. This was his first interview since he left for Saudi Arabia in November 2009.
It is not clear if he will be able to return to perform his duties within the two-week deadline.
President Yar'Adua is being treated for inflammation of the lining around the heart and has a long-standing kidney complaint.
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