The State Department said Friday it was "troubled" by reports that a Chinese blogger who met top US diplomat John Kerry had been fired by his employer.

Journalist Zhang Jialong was one of four bloggers who met Kerry in Beijing in February, when he urged the United States to help "tear down the great Internet firewall."

Zhang told AFP Sunday he had lost his job at Internet firm Tencent for "leaking business secrets and other confidential and sensitive information," in what he said was a reprisal for meeting Kerry.

"We are deeply concerned by reports that one of the bloggers who met with the secretary has been fired from his job after meeting with secretary Kerry," the State Department said.

"If the reports are true, we would be very troubled that a private company employee would be fired for expressing his or her views."

In a separate statement, the State Department also voiced concerns over the arrest of a Chinese reporter working for the Japanese newspaper Nikkei.

The detention of Xin Jian "appears to be part of an ongoing crackdown on freedom of expression that has targeted bloggers, journalists and others," it said.

Media censorship and detaining reporters researching sensitive stories was "incompatible with China's aspirations to build a modern, information-based economy and society."

Washington urged Beijing to guarantee all its citizens freedom of expression as well as the freedom of the press.