KUALA LUMPUR, Malaysia - Malaysian authorities have begun sweeping the airport terminal where North Korean ruler Kim Jong Un's half brother was killed to check for possible traces of the nerve agent that was suspected to have been used in the attack.

The investigation has unleashed a serious diplomatic fight between Malaysia and North Korea, a prime suspect in the Feb. 13 killing of Kim Jong Nam at Kuala Lumpur's airport. Friday's revelation by Malaysian police that the banned chemical weapon VX nerve agent was used to kill Kim raised the stakes significantly in a case that has broad geopolitical implications.

The sweep started around 2 a.m. Sunday with parts of the departure hall of the budget terminal, where Kim was killed, cordoned off. It involved officers from the police's chemical, biological, radiological and nuclear teams, as well as the fire department's hazardous materials unit and the government's atomic energy board.

Police officials say no flights are scheduled at the terminal during the sweep.