The United Nations Secretary General, Kofi Annan, has called on China to step up Aids prevention measures or face an explosive epidemic.

Addressing students in the eastern city of Hangzhou, Mr Annan urged the authorities to take immediate action.

China has everything to gain if it can stem the tide of the Aids epidemic, and everything to lose if it fails

Kofi Annan

"China is facing a decisive moment," he said.

"There is no time to lose if China is to prevent a massive further spread of HIV/Aids."

A UN report recently warned that 10 million people in China could be infected with the disease by the end of the decade.

'Explosive' epidemic

Speaking at the start of a two-day visit to China, Kofi Annan said the country stood "on the brink of an explosive Aids epidemic".

While he was careful to give credit to China's efforts in focusing public attention on Aids, the BBC's Shanghai correspondent Francis Markus said Mr Annan's message was unequivocal.

The Chinese leadership, Mr Annan said, needs to do more to intensify the campaign and promote greater openness in dealing with the issue.

10 million people could be infected by 2010, a UN report estimates

The UN Secretary General urged his audience of university students to speak openly about the illness, which retains a deep stigma in China for its popular associations with homosexuality and drug use.

"Silence is death," he said.

Failure to deal with the problem would cause a host of problems including a rise in orphaned children and a burden on social services and businesses, Mr Annan warned.

"Clearly, China has everything to gain if it can stem the tide of the Aids epidemic and everything to lose if it fails to do so," he said.

His message reinforces a recent report by UN Aids officials, which said the country faced an "Aids catastrophe".

China has undoubtedly begun to address the issue more frankly, our correspondent says.

But activists point to the recent detention of a Chinese Aids campaigner and the restrictions on journalists trying to report on the disease, as evidence the government is anxious about Aids as a political issue as well as an illness.

Iraq discussions

Mr Annan, who arrived in China late on Sunday, was scheduled to fly to Beijing later on Monday for talks with President Jiang Zemin, which are also expected to cover the current international crisis over Iraq.

Beijing, one of five permanent UN Security Council members, has expressed disquiet over US calls for military action against Iraq, and has called for a political settlement.

After leaving China, Annan will visit Mongolia, Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan and Turkmenistan on a trip lasting until 23 October.