BAKU - The likelihood that 80-year-old Heidar Aliyev will stay on as president of Azerbaijan receded on Friday when doctors at his U.S. clinic said the veteran politician was suffering from heart failure and kidney problems, AFP said. In a statement reported by Azerbaijan's official news agency, the Cleveland Clinic Foundation in Ohio said: "President Aliyev... is currently being treated for congestive heart failure, which includes some kidney problems." It added: "He has responded favorably to initial treatment. He has no neurological problems. He is resting comfortably in the Department of Cardiovascular Medicine."

The statement from the clinic, where Aliyev checked in on Wednesday after being flown from a military hospital in Turkey, was the frankest admission yet of the seriousness of the Azeri leader's condition.

Although Aliyev shocked his compatriots by collapsing while making a televised speech in April, up until now officials in the oil-rich former Soviet republic, where the government keeps a tight control over the flow of information, have said only that he had an unspecified heart problem.

Some had even maintained that he only had cracked ribs.

Congestive heart failure is a condition when the chambers on one or both sides of the heart are unable to pump enough blood to supply the body, according to the web site of the American Heart Association.

Kidney problems are often associated with the condition, because the body copes by diverting blood away from less important organs to maintain the blood supply to the heart and brain.

Treatment ranges from medication to improve circulation, heart bypass surgery, which increases the flow of blood to the heart, or, when other options have failed, heart transplant surgery.

Aliyev has already undergone bypass surgery, at the Cleveland clinic back in 1999, and unconfirmed reports, quoting his doctors in Turkey, claimed that he needed nothing short of a transplant.

The Cleveland Clinic has a specialist heart centre, which according to its own advertising material performs more open heart surgery than any other institution in the U.S., and has carried out numerous heart transplants.

The political ramifications of Aliyev's condition are limited. His son Ilham, who was appointed prime minister on Monday, will take over as caretaker president if his father leaves office, ensuring a smooth handover of power.

But news of Aliyev's heart failure signaled that the curtain was finally coming down on a political career of remarkable longevity.

After serving in the KGB, the Soviet Union's secret police, Aliyev was appointed Azerbaijan's Communist Party chief in 1969, beginning his dominance of politics in the republic that has lasted over three decades.

A protege of Soviet leader Leonid Brezhnev, he was promoted to the Politburo in 1982. As a member of the Communist old guard, he was swept aside by the perestroika reforms in the late 1980s.

But in 1993 he was back, taking advantage of an attempted military coup to have himself installed as leader of a newly-independent Azerbaijan.

Many critics say he is an elected dictator, but he restored stability to the restive republic, ended a war with neighboring Armenia and attracted billions of dollars (euros) in investment from western oil companies.

As news of Aliyev's heart failure reached Azerbaijan's capital, Baku, there was skepticism that he could pull off another comeback. "You have to feel sorry for the poor old boy," said one Western diplomat.

"I've heard you can operate on these sort of conditions but he's 80 years old. Surely he can't take any surgery?" said Ravilya, a housewife.