The Los Alamos lab was originally set up in 1943 to build the first atomic bomb and is now one of the biggest research centres in the world. Recently, however, the laboratory has been involved in several high-profile controversies, including credit card misuse by employees, the disappearance of millions of dollars worth of computer and other equipment, and a failed attempt to prosecute Los Alamos physicist Wen Ho Lee for allegedly giving weapons secrets to China.

“As Laboratory director, I accept personal accountability for everything that happens here, both good and bad,” said Browne in his official resignation statement.

Browne joined Los Alamos in 1979 as a group leader in the physics division and became director in 1997. The principal deputy director, Joseph Salgado, has also resigned. The laboratory will now be led, on a temporary basis, by George Nanos, a retired Navy admiral.