BEIJING (AFP) - - Strong winds helped clear Beijing's skies on Tuesday of the pollution that is threatening the Olympics, but authorities hoping to breathe easy faced pressure over China's human rights record.

After a dismal few days when athletes arriving for the Games were greeted by heavy smog, visibility across the Chinese capital dramatically improved thanks to the winds and Beijing claimed success in its anti-pollution battle.

"We have seen comprehensive measures implemented already and we have seen that they have had comprehensive results," Beijing Environmental Protection Bureau deputy director Du Shaozhong said 10 days out from the Games.

He cited the raft of short-term fixes taken since the start of the month, such as taking one million cars off the road and closing down more than 100 polluting factories, for an improvement of over 20 percent in the air quality.

However it appeared the winds, powered partly by a tropical storm to the southeast, were the key factor in the turnaround from Monday, and Australian Olympic Committee president John Coates said pollution concerns remained.

"There doesn't appear to be a great improvement," Coates said, comparing the situation with when he was last in the Chinese capital in March.

"Let's hope that there are more solutions and that they will kick in and there will be an improvement, that's what we're all hoping for," added Coates, who arrived in Beijing on Monday along with some Australian athletes.

One other controversy swirling around the Games has been the human rights record of China's communist leaders, and Amnesty International and other critics stepped up the pressure over the issue.

"Unless the authorities make a swift change of direction, the legacy of the Beijing Olympics will not be positive for human rights in China," Amnesty said in a report.

"In fact, the crackdown on human rights defenders, journalists and lawyers has intensified because Beijing is hosting the Olympics."

New Zealand Prime Minister Helen Clark also put her name to an Amnesty campaign aimed at pressuring China to improve its rights record ahead of the Games, the rights group said in Wellington.

Clark signed an Amnesty "Olympic legacy banner" and added the message: "My wish is that all nations stop executions."

Adding to rights groups' concerns, a Chinese lawyer said a Beijing-based activist who had campaigned for the rights of people evicted from their homes for the Olympics would go on trial Monday, four days before the Games start.

Ni Yulan , a 47-year-old former rights lawyer who was disbarred in 2002, has already been detained for three months, according to her lawyer, Hu Xiao.

Ni had spent most of this decade assisting victims of forced eviction in the Chinese capital, many of whom lost their homes to make way for Olympic facilities.

Nicholas Bequelin, a Hong Kong-based researcher with Human Rights Watch, said Ni's situation was part of a much bigger problem.

"There's no doubt that the Olympics have had a very negative impact on the human rights situation in China," Bequelin told AFP.

Chinese foreign ministry spokesman Liu Jianchao hit back at Amnesty and other critics, defending the government's human rights record.

"Anybody who knows about China will not agree on this report on the deterioration of the Chinese human rights situation," Liu said in response to the Amnesty report.

"We hope it can take off the coloured glasses it has worn for many years to see China in an objective way."