A former senior official of the US Department of State was arrested on Wednesday on a charge of passing documents to Taiwan intelligence agents and concealing a trip to Taiwan.

The high-ranking official, Donald W. Keyser, met one of the agents in Taibei last September during a trip to China and Japan, local media reported Thursday, quoting US law enforcement and intelligence officials, and court papers as saying.

Keyser, 61, who was tailed by the FBI (Federal Bureau of Investigation) in recent weeks, conducted a series of covert meetings with two Taiwanese agents around Washington.

He was also charged with making a false statement to the FBI in a government background check.

Keyser was promoted to deputy assistant secretary for East Asian and Pacific Affairs this year and was reported to have advised Secretary of State Colin Powell on China issues.

Keyser was a Foreign Service officer for three decades and retired in July as the No. 2 person in the US State Department's East Asia Bureau.