A US official said the United States has closed its embassy in Libya's capital after evacuating all personnel on a ferry and a chartered plane.

The Tripoli embassy's operations were suspended because of the deteriorating security situation, the official said.

The last embassy staff departed on a chartered flight at 5.49 p.m.

The official spoke on condition of anonymity because of the extreme sensitivity of the situation.

The White House says the US is moving forward with plans to impose sanctions on Libya in response to violence there.

President Barack Obama's spokesman Jay Carney says the US is finalizing that process and that the US is also working with European partners on additional sanctions and other multilateral actions that could be taken.

The announcement today comes as hundreds of Americans were evacuated from Libya following days of violence. Militias loyal to Moammar Gadhafi have been firing on protesters demanding the Libyan leader's ouster.

Mr Carney says President Obama will meet with the UN Secretary-General Ban Ki-moon in Washington on Monday to discuss the situation in Libya.