President Barack Obama on Wednesday strongly condemned the killing of the US ambassador to Libya and three other embassy staff as an "outrageous attack" and ordered increased security at U.S. diplomatic posts worldwide, reports Reuters.

"I have directed my administration to provide all necessary resources to support the security of our personnel in Libya, and to increase security at our diplomatic posts around the globe," Obama said in a statement after the U.S. diplomats were killed in a rocket attack on their car in Benghazi.

"While the United States rejects efforts to denigrate the religious beliefs of others, we must all unequivocally oppose the kind of senseless violence that took the lives of these public servants," he said.