The United States informed Japan and South Korea on Monday that it has started a review of whether to put North Korea back on a list of state sponsors of terrorism, South Korea's Yonhap news agency said.

Quoting a senior South Korean official, Yonhap said the Feb. 13 killing of Kim Jong Nam, the half brother of North Korean leader Kim Jong Un, in Malaysia, in which Pyongyang's involvement is suspected, prompted the United States to take such action.

"I believe the U.S. (government) will take into account reactions from Congress," the official was quoted as saying, referring to growing calls among U.S. lawmakers for relisting North Korea as a state sponsor of terrorism. Washington removed Pyongyang from the list in 2008.