US House Speaker Nancy Pelosi condemned China on Wednesday of arresting the leading pro-democracy advocate Liu Xiaobo.

Liu Xiaobo, 53, one of the Chinese best known dissidents, has been formally arrested on suspicion of inciting subversion, state media reported Wednesday.

State-run Xinhua news agency said prosecutors approved Liu's arrest by Beijing police Tuesday for alleged agitation activities aimed at subversion of government and overthrowing of the socialist system.

Liu's arrest for peacefully criticizing his government and advocating for human rights violates provisions in China's constitution as well as international human rights standards, Pelosi said in a statement.

The decision by the Chinese government to formally arrest Liu Xiaobo deserves the full condemnation from the international community, she said.

Liu, who was involved in the 1989 Tiananmen pro-democracy protests, has been detained since December after signing Charter 08, a widely circulated petition that called for greater democracy and the rule of law in China.

If indicted and convicted, the 53-year-old dissident could be sentenced to a maximum of 15 years in prison, according to Mo Shaoping, an attorney who has been barred from representing Liu because the lawyer also signed the Charter 08 petition.

The Charter 08, a widely circulated manifesto calling for fundamental political and legal reforms to China's Communist Party-dominated system, was signed by about 300 Chinese scholars, lawyers and officials.