WASHINGTON (AFP) — US House Speaker Nancy Pelosi, a tough critic of Beijing's human rights record, has urged the Chinese government to release 10 "prisoners of conscience," her office said Tuesday.

During a visit to China last week, Pelosi asked Chinese President Hu Jintao to free the prisoners, among them dissidents, pro-democracy activists, journalists and pro-Tibetan advocates.

The request in a letter dated May 27 came ahead of the 20th anniversary of the 1989 Tiananmen Square pro-democracy protests which ended in a brutal and bloody crackdown by the Chinese army.

Pelosi on Tuesday rejected criticism that she had not pressed China on human rights during her weeklong trip that ended on Sunday.

"We had an agenda that focused on climate change but any agenda that we have with the government of China will also include human rights," she told reporters.

"Unless we talk about human rights in China and Tibet, we abrogate all authority to talk about human rights any place in the world."

The speaker's list included leading Chinese dissident Hu Jia, who was first detained in December 2007. In October 2008, Pelosi had commended the European Parliament for its "bold decision" to award him the Sakharov Prize for Freedom of Thought.

She called for the release of Liu Xiaobo, a prominent human rights activist who was detained and transported to an undisclosed location in December 2008.

He was one of the original signers of Charter 8, which calls for democratic reform in China and has been signed by more than 300 Chinese people.

Pelosi also urged Hu to free prominent human rights lawyer and rights advocate Gao Zhisheng, who was taken by state security personnel on January 19 and has not been heard from since.

Gao, once a prominent lawyer and communist party member, has been an outspoken defender of people seeking redress from the government including coal miners, underground Christians and the banned Falungong spiritual movement. He is also suspected of having been tortured during a previous arrest in 2007.

"It is my understanding that these individuals are prisoners of conscience and they are detained or imprisoned for exercising rights that are guaranteed to them under Chinese law or under international human rights conventions that have been signed or ratified by the Chinese government," she wrote to Hu in a letter dated May 27.

The first female speaker of the House of Representatives, Pelosi's past criticism of Chinese rule in Tibet has drawn the wrath of Beijing, which has called her words foreign interference in its internal affairs.

In her letter, she pressed for the release of Tibetan lama Bangri Chogtrul Rinpoche, who founded a children's school in the Tibetan capital Lhasa, and Ronggyal Adrag, who was detained in 2007 after shouting slogans calling for the return to Tibet of spiritual leader the Dalai Lama.