Ethiopian prime minister Meles Zenawi not seen for seven weeks Addis Ababa mute on whereabouts of PM – latest African leader believed to be unwell but subject of information blackout

He hasn't been seen in public since the G8 summit in Mexico, and since then Ethiopia's prime minister, Meles Zenawi, has even missed the African Union summit held in his own capital city, Addis Ababa.

Zenawi, 57, usually a conspicuous figure at meetings of African and international heads of state, has now been missing for more than seven weeks, amid growing incredulity.

Government sources in the secretive African nation say that Meles – who was seen looking frail before his disappearance – is resting but well, but more than one eyebrow has been raised at the reasons for his absence. "The Prime Minister is on vacation recovering from illness," an Ethiopian government source told the Guardian. "There has been a lot of ill-meant speculation about his health."

But there have been numerous reports that Meles traveled to Europe for medical treatment, prompting debate about its success as his recovery period continues unabated. Some media reports have claimed Meles visited the Saint-Luc hospital in Belgium, while the Egyptian state information service reported that Meles underwent surgery in Germany, prompting a cable of good wishes from President Mohamed Morsi.

The Ethiopian press – regarded as one of the least free in Africa – has also reported that Meles is recovering from medical treatment. Experts say there is widespread confusion as to the fate of the prime minister, even within the secretive ruling party, the Tigray People's Liberation Front (TPLF).

"It is a mystery what has happened to Meles and not even his own ministers know his fate," an exiled Ethiopian source said. "Media in Ethiopia have been getting it wrong and have now dropped the story altogether." Some analysts have claimed that Meles will not return to power at all, after a senior member of the TPLF, Sibhat Nega, stated that the party was working on a power succession and that the regime could continue in the event of "individuals" dying or leaving the government.

The death of president John Atta Mills in Ghana last month led to a rare broadcast on Ethiopian state TV on how to mourn the death of a leader, which has also fuelled speculation that Meles's health may be further deteriorating. It is not the first time that an African government has failed to confirm the illness or death of a leader in office, prompting periods of mysterious absence.

A century ago Emperor Menelik II, the founder of modern imperial Ethiopia, was buried in 1913 without any public announcement after he had been incapacitated by a stroke for several years, leaving the administration of the country in the hands of a specially appointed council.

More recently, the late Nigerian president Umaru Yar'Adua was neither seen nor heard from for almost six months – apart from one phone interview with the BBC – between travelling to Saudi Arabia for medical treatment, and his eventual death in May 2010.

Earlier this year news of president Bingu wa Mutharika of Malawi's death was leaked to the press, but not confirmed by the government for 24 hours, prompting fears of a power struggle and nearly triggering a constitutional crisis before he was eventually succeeded by the current president, Joyce Banda.

The tendency to shroud the sickness and deaths of leaders has been repeatedly criticised for destabilising often fragile democracies and triggering secretive succession crises. There have been a flurry of searches and social media interactions on the fate of Meles by Ethiopians – including a popular #WhereIsMeles hashtag on twitter, but his absence from government is of concern to donors, who pump almost $4bn (£2.6bn) of aid into Ethiopia every year.

It is thought that deputy prime minister and foreign minister, Hailemariam Desalegn, is temporarily in charge, alongside other members of the ruling party. But one diplomatic source in Addis Ababa said that no western government was sure as to the whereabouts or fate of the Ethiopian leader.

Meles, who came to power in 1991 following a 30-year war that toppled the Soviet-backed regime of former president Mengistu Haile Mariam, has long been popular with donors for his record of delivering growth to Ethiopia, whose economy has been growing at an estimated 9% per year for almost a decade.

Ethiopia receives hundreds of millions of dollars in aid and support from the US, which welcomes its peacekeeping and military intervention in neighbouring conflicts in Somalia and Sudan. But Meles is viewed by many as a dictator who has stifled democracy and used draconian methods to silence dissent. The Committee to Protect Journalists, which regularly condemns the trial and imprisonment of journalists in Ethiopia, says that one newspaper – the weekly Feteh – was ordered by the government to block dissemination of 30,000 copies reporting on the prime minister's whereabouts.

"The ban on Feteh's latest issue illustrates the depth of repression in Ethiopia today and authorities' determination to suppress independent coverage of the prime minister," said Tom Rhodes of the CPJ. "Every citizen has a right to be informed about the wellbeing of their leader and the conduct of their government."