At least nine Nigerian newspaper front pages carried a statement, which they said had been signed by more than 50 public figures, calling on Yar'Adua to resign immediately or allow a medical panel to determine his ability to rule.

The 58-year-old leader was flown to a clinic in Saudi Arabia nine days ago after complaining of chest pains and has been diagnosed with acute pericarditis, an inflammation of the membrane around the heart that can restrict normal beating.

The cabinet said it had taken note of the calls to invoke article 144 of the constitution, which states the president ceases to hold office if a two-thirds cabinet majority passes a resolution declaring him incapable and the declaration is then verified by a medical panel including his personal doctor.

But Justice Minister Michael Aondoakaa told reporters a full disclosure by Yar'Adua's chief physician showed he was recovering from a "small illness which can befall any one of us."

"Unless somebody produces any contrary medical evidence ... council has ruled that there is no basis to consider section 144," he said.

The Daily Trust newspaper, citing Nigerian officials in Saudi Arabia, said earlier that Yar'Adua was out of intensive care but that only his wife and Nigeria's ambassador to Saudi Arabia had been allowed to visit him.

Mahmud Yayale Ahmed, who as secretary to the federal government coordinates between the presidency and ministries, said government business was continuing normally.

"Since (Yar'Adua's departure) we have convened two council meetings, one last week, and today. Apart from these, every other aspect of governmental activity is being conducted well, and the Vice President, as usual, is in charge," he said.

"On issues that would require Mr President's express approval, contacts are being made and such approvals do come."

CALLS TO RESIGN

Yar'Adua's stay in a clinic in the Red Sea port of Jeddah is the latest in a series of overseas medical trips which have raised concern about his fitness. He has in the past visited Saudi Arabia and Germany to treat a chronic kidney problem.

The statement published in the newspapers said Yar'Adua should either resign or request the cabinet invoke article 144 and pass a resolution stating that he appears incapable, allowing a medical panel to determine his fitness.

The list of names reported to have signed the statement includes former presidential candidates, former state governors, a former Senate president and a former chief of defence staff.

"It is clear to every discerning observer that President Umaru Yar'Adua's physical condition has had a negative impact on his ability to discharge the functions of the highest office in our nation," the statement said.

Nineteen politicians from Yar'Adua's northern home region published a separate advertorial saying the constitution must be respected should he be unable to continue in office.

The ruling People's Democratic Party (PDP), which has accused the opposition of deliberately generating "hype and tension," condemned the resignation calls as "unpatriotic."

But the Action Congress opposition party said there was nothing wrong with public debate about Yar'Adua's health.

"Over a year ago, we advised the government to be more forthcoming on the issue of the president's health, in order to stem the wild rumours over it," AC spokesman Lai Mohammed said.

"Unfortunately that advice was not heeded until the issue became critical this time."

Vice President Goodluck Jonathan would take over if the president resigns or becomes permanently incapable of discharging his functions, according to the constitution.

Jonathan's office on Saturday issued a statement urging "all well-meaning Nigerians to continue to give support to the President Yar'Adua administration" and repeating that there was no cause for alarm over his health.