Victor H. Reis submitted his resignation on Friday. He declined to comment on his decision, but The Washington Post quoted unnamed officials who said it stemmed from disagreements on how to improve security at the laboratories.Reis was one of several officials who came under fire after a Congressional investigative panel last month accused China of stealing secrets to every key American nuclear warhead made since the 1970s and passing data to US foes.

The report drew attention to glaring lapses in US security and counter-intelligence.

Some Republicans have called for creating an agency within the Department of Energy to oversee security and counterespionage efforts, an approach Reis reportedly supported. Energy Secretary Bill Richardson resisted such amove.Reis' resignation comes as the US Government is reviewing its efforts to combat espionage.

Federal Bureau of Investigation (FBI) director Louis Freeh has proposed creation of a new division of his agency to combat espionage, The New York Times said in its Saturday's editions, quoting unnamed government officials.Freeh's proposal calls for the FBI's national security division to be split into two separate entities, one devoted to fighting terrorism and the other to locating spies, the Paper said.

Since the collapse of the Soviet Union, the officials said fighting terrorism had become more important as intelligence agencies believed the threat posed by spies would decrease.

Currently, one FBI division is charged with both fighting terrorism and espionage. The split would ensure both areas received enough attention, officials told the Paper.

Attorney General Janet Reno has approved Freeh's recommendation and sent it to The White House, the paper said.