It is hard to imagine what life must be like for Aung San Suu Kyi, locked up inside her Rangoon home, separated from her children, denied visitors, her phone line cut, her mail intercepted. Burma's opposition leader, whose 1990 election victory was annulled by the military, is now in her 13th year of detention. She has been held continually since 2003. In June she spent her 63rd birthday alone.

Unconfirmed reports suggest Suu Kyi, who has suffered health problems in the past, is unwell again. Her lawyer, Kyi Win, who was allowed to see her last month, quoted her as saying: "I am tired and I need some rest." Following her refusal of a food delivery, there is also speculation the pro-democracy campaigner and Nobel peace prizewinner has begun a hunger strike. Her lawyer said her weight had fallen below the 7st she was known to weigh in 2003.

While uncertainty surrounds Suu Kyi's plight, there is nothing at all ambiguous about Burma's political, social and human rights situation one year after the junta brutally suppressed the Buddhist-monk-led "saffron revolution". By almost any measure, it is distinctly worse. Last May's Cyclone Nargis disaster played its part. But most of the deterioration is man-made.

Despite last autumn's storm of international condemnation and impassioned calls for action, the junta continues to hold more than 2,000 political prisoners, including leaders of Suu Kyi's National League for Democracy (NLD) such as U Win Tin, in jail since 1989. UN attempts to foster political reform have got nowhere. And trade sanctions imposed by the US and EU are being undermined by the generals' energy deals with China, Thailand and India. Oil and gas sales topped $3.3bn (£1.85bn) last year.

According to Benjamin Zawacki of Amnesty International, half a million people are internally displaced. He said the army is continuing "systematic" rights violations against Karen and other ethnic minorities including "extrajudicial killings, torture, enforced disappearances, arbitrary arrests, forced labour, crop destruction [and] restrictions of movement".

Amid some of the worst poverty, health problems and corruption in the world, many people now have only one wish: escape. Even long-suffering Zimbabweans have an option to flee to neighbouring countries. But the Burmese are locked in, held down by their rulers and not wanted in India, China or Thailand. With an estimated population of more than 50 million, Burma has become the world's biggest prison camp.

"The UN mission has been a complete failure," said Mark Farmaner, director of Burma Campaign UK. Since Ibrahim Gambari, a former Nigerian foreign minister, was appointed special envoy in May 2006, the number of political prisoners had doubled, ethnic cleansing in eastern Burma had intensified, and humanitarian aid for Cyclone Nargis victims was blocked, he said.

"There has been a massive deterioration in the human rights situation. But during Gambari's last two visits no senior member of the regime bothered to see him," Farmaner said. "He is seen as biased towards the regime and we think he should resign. He no longer has the respect or confidence of either side."

Criticism of Gambari was also voiced by the NLD. It said his visits, the last of which ended on August 23, had produced "no positive developments". The party said the UN envoy's offer to help the junta organise elections in 2010 under a new constitution that the opposition rejects had undermined his independence. For her part, ill or not, Suu Kyi twice refused to meet Gambari, reportedly leaving him standing on her doorstep.

Farmaner said the time had come for Ban Ki-moon, the UN secretary-general, to take personal charge before the country exploded again. He is due to visit Burma in December following talks with Asian leaders. "There have been 37 UN visits in 20 years but things just get worse. Now they need to set timelines and benchmarks which the junta must meet. The first benchmark should be the release of all political prisoners," he said. It was also essential the UN security council fully back the process, and be ready to pass a punitive resolution if the generals did not comply.

Farmaner praised Gordon Brown who he said was personally committed to ending the impasse and actively raised Burma at the UN and in other forums. But other western leaders, and countries with real leverage such as China, were less concerned now the media spotlight illuminated by last autumn's revolt had shifted elsewhere.

"There is an increasing sense of desperation," Farmaner said. "People were very depressed after the uprising, very frightened. But there was hope that Gambari would do something. Now that hope has gone and there is even more repression than before. At the moment, the fear is stronger than the anger. But that could change."