WASHINGTON - US President Barack Obama on Wednesday strongly condemned the attack that killed the US ambassador in Libya and three other Americans.

"I strongly condemn the outrageous attack on our diplomatic facility in Benghazi, which took the lives of four Americans, including Ambassador Chris Stevens," he said in a statement released by the White House.

Expressing his condolences and support to the families of the victims, Obama said he has given orders 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."

Hundreds of protesters, angered by an alleged US-made movie that insults Prophet Mohammed, stormed the US consulate building in Libya's eastern city Benghazi on Tuesday night. US Ambassador Stevens was killed in the conflict.

The US ambassador, who was on a short trip to Benghazi, died from suffocation as a result of smoke inhalation, as protestors set fire at the scene, the pan-Arab Al-Jazeera TV reported Wednesday. Three staffers were also killed during the fierce clashes.

"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," Obama said in the statement.

US Secretary of State Hillary Clinton also condemned the attack in a statement released by the US State Department.

"We condemn this vicious and violent attack that took their lives, which they had committed to helping the Libyan people reach for a better future," she said.

According to the State Department website, Stevens was appointed as the US ambassador to Libya in May.