Some 50 Marines were sent to Libya on Wednesday to reinforce security at U.S. diplomatic missions after Washington's envoy to the North African nation was killed in an attack in Benghazi, CNN reported Wednesday.

The Marines departed from the U.S. base in Rota, Spain, the network said.

Ambassador Chris Stevens and three other Americans died in the attack on the U.S. Consulate in Benghazi by Muslim militants angry over an anti-Islam video produced by an Israeli filmmaker based in the United States.

President Barack Obama said Wednesday in a joint appearance at the White House with Secretary of State Hillary Clinton that he had ordered security measures in Libya stepped up after the attacks.

"We're working with the government of Libya to secure our diplomats. I've also directed my administration to increase our security at diplomatic posts around the world," Obama said.

Before the attack in Libya, dozens of demonstrators had invaded the U.S. Embassy complex in the Egyptian capital, where they tore down the U.S. flag, also in protest over the anti-Islam video.

"Since our founding, the United States has been a nation that respects all faiths," the president said Wednesday. "We reject all efforts to denigrate the religious beliefs of others. But there is absolutely no justification to this type of senseless violence. None. The world must stand together to unequivocally reject these brutal acts." EFE