A top Chinese minister defended the legacy of the 2008 Beijing Olympics on Sunday, citing an improved environment just as authorities in the capital face pressure to act on heavy pollution.

Vice sports minister Yang Shu'an was speaking at a briefing also attended by London Olympics chairman Sebastian Coe, in Beijing for an international meeting with the Paralympic movement to promote awareness of the disabled.

"The legacies of the Games for the Chinese people and those living in Beijing are multifaceted. But the first two are an improved transport infrastructure and environment," he told reporters.

"Everybody living in Beijing has realized the unique opportunities created by the Olympics and can see... the overall environment has improved."

The International Olympics Committee (IOC) and Chinese government said at the time of the Beijing Games in 2008 that improved air quality would be a major legacy of the sporting event.

But in recent months, the capital has often been shrouded in a cloud of smog, with many blaming the perpetually gridlocked roads of Beijing and China's continued reliance on fossil fuels to meet its energy needs.

The government is facing increasing pressure from the capital's residents to change the way it monitors pollution, amid accusations authorities are underplaying the problem.

Yang admitted there were "challenges to sustain the Olympic legacies", pointing to environmental protection as one of the issues.

Another major legacy promoted by the IOC was an improved human rights record, but pressure groups say this has deteriorated since the end of the Games.

This year, scores of activists and dissidents were detained amid government concern over the wave of democracy protests sweeping the Arab world.

Coe, an IOC member, told reporters "it would be entirely inappropriate to get into human rights".

"But I do genuinely think sport helps in this (improvement of human rights) process," he said, pointing to the Seoul Olympics in 1988, seen as a pivot to South Korea's transition to democracy.

Coe also defended the hike in budget for the London 2012 Olympics opening and closing ceremonies, saying the extra 41 million pounds handed over by the government last Monday would produce the "largest piece of television ever".

"The government saw what we have created in the main ceremonies and wanted to invest more in this unique promotion of Britain to four billion people around the world," he said.