PHNOM PENH, Jan. 31 (Xinhua) -- The United States on Thursday opened here a new overseas branch of its Federal Bureau of Investigation (FBI), officially called the embassy's Legal Attache Office.

　　Visiting FBI Director Robert Mueller and U.S. Ambassador to Cambodia Joseph Mussomeli cut the ribbon for the opening ceremony at the U.S. Embassy in Phnom Penh.

　　The office will work with the Cambodian national police authorities to crackdown on cross-border crimes and terrorism acts, said Mueller.

　　Both sides will cooperate closely to exchange information and jointly carry out operations against such crimes, he said.

　　U.S. will also help train the Cambodian police force to benefit the law enforcement in the kingdom, he added.

　　Mueller arrived here on Wednesday for a two-day official visit to Cambodia to expand bilateral legal cooperation. He had met with Prime Minister Hun Sen and other government officials.

　　A Princeton graduate and highly decorated member of the U.S. Marine Corps, Mueller became the sixth director of FBI in 2001 after serving as the acting deputy attorney general in the U.S. Department of Justice.