US President Barack Obama on Thursday called his Yemeni counterpart Abd-Rabbu Mansour Hadi over the security of American personnel and diplomatic facilities in the Arab nation, where demonstrators stormed the US embassy to protest against an anti-Islam movie that insults the Prophet Mohammed.

In the phone conversation, Obama expressed "concern about the security of American personnel and diplomatic facilities in Yemen," the White House said in a statement.

It said Hadi pledged to do "everything possible" to protect American citizens in Yemen, and said he had deployed additional security forces around the US embassy.

The protesters broke into the embassy earlier in the day, damaging equipment and cars inside, including the US ambassador's armored vehicle, and set on fire parts of the embassy building. An American flag was burned as well.

The clashes between angry demonstrators and security forces around and inside the US embassy have resulted in three deaths, all protesters, and up to 30 injuries.

Hadi had apologized to Obama over the attack and ordered an investigation.

Similar protests have broken out in Libya, Egypt, Tunisia, Iran and Iraq, and US Ambassador to Libya Chris Stevens and three other American diplomats died on Tuesday night in the US consulate in Libya's eastern city of Benghazi, a tragedy that has shocked the United States as well as the world.