BEIJING — Chinese authorities released a leading human rights activist and lawyer from confinement on Friday, one day after American officials raised public concerns about his detention at the conclusion of a two-day human rights dialogue with Chinese representatives.

The activist, Teng Biao, is a Beijing university lecturer and lawyer who has given legal counsel to a series of government critics, including Tibetan dissidents, opponents of government land confiscations and members of Falun Gong, a banned spiritual group. He was among the original signers of Charter 08, a pro-democracy manifesto that led to the imprisonment of one of its authors, Liu Xiaobo, who was awarded the Nobel Peace Prize last October.

Mr. Teng disappeared on Feb. 19 when security officers detained him after a lunch with other activists to discuss the case of another human rights lawyer who is under house arrest. He had not been heard from since.

The United States Embassy in Beijing confirmed his release.