State Department spokeswoman Victoria Nuland told reporters that "all of the processing on the US side has been completed" to provide visas to Chen, his wife and two children.

"We are ready when he and his government are ready. We have been for more than a week now in terms of his visa to come pursue his studies," Nuland said.

She said Chen has informed US officials through daily contacts that Chen's "conversations, contacts and processing continue" on the Chinese side.

US officials said May 4 that China would allow the blind self-taught lawyer to leave soon to study in the United States, after he dramatically fled house arrest and took refuge in the US embassy.

Chen, who angered authorities by exposing forced abortions and sterilization under China's one-child policy, remains in a Beijing hospital for treatment of injuries, with Chinese officials publicly quiet on his case.

New York University has said it has invited Chen to be a visiting scholar at NYU, either in New York or one of the institution's global sites.

China said it had launched "solemn representations" with London after Tibet's exiled spiritual leader held a private meeting with Cameron and his deputy on Monday during a visit to London to collect a lucrative prize.

Beijing has in the past strongly objected when the Dalai Lama, who seeks greater autonomy for Tibet from its Chinese rulers, has met Western leaders.

A British government spokeswoman told AFP: "We don't want to see our relationship with China disrupted by the Dalai Lama's visit."

But she added: "The Dalai Lama travels all over the world. He has visited the UK on several occasions and met with previous prime ministers.

"It is for the prime minister and deputy prime minister to choose who they see. The Dalai Lama is an important religious figure and advocate for peace and the prime minister regularly meets with such figures."

The meeting was held at St Paul's Cathedral, where the Dalai Lama was collecting the �1.1 million ($1.8 million, 1.4 million euros) Templeton Prize, rather than at Cameron's Downing Street residence.

But the spokeswoman denied that the meeting was deliberately held away from Cameron's residence to avoid angering China.

"Previous governments have generally met the Dalai Lama in a religious location," she said.

The Dalai Lama, who fled his homeland for India in 1959 after a failed uprising against Chinese rule, said on Monday that he would donate the prize to charity, with $1.5 million going to Save the Children's operations in India, where he is exiled.