Staff and wire reports

An Islamist militia has reportedly seized a U.S. Embassy residence in Tripoli, although U.S. officials cautioned that they have been unable to confirm the takeover.

The U.S. ambassador to Libya, Deborah Jones, acknowledged on Twitter Sunday that an online video of a building overrun by crowds of people "appears to be a residential annex of the U.S. Mission."

But she added that she could not confirm this. "To my knowledge & per recent photos the US Embassy Tripoli chancery & compound is now being safeguarded and has not been ransacked," she wrote on Twitter. A State Department spokeswoman, Katherine Pfaff, said Sunday she had no information on the alleged seizure.

The video posted shows unarmed men playing in a pool at the compound, jumping into it from a second-story balcony. Voices heard in the video identified it as the U.S. Embassy compound.

An Associated Press journalist reported walking through the two-story structure Sunday -- its windows broken -- after an umbrella group for Islamist militias, Dawn of Libya, invited onlookers inside. The journalist reported seeing treadmills, food, televisions and computers still inside.

The alleged seizure occurs a month after American personnel were evacuated because of growing violence in Libya.

Sept. 12 will be the two-year anniversary of the killing of U.S. Ambassador Chris Stevens and there other Americans in Benghazi, Libya's second largest city.

A commander for the Dawn of Libya group, Moussa Abu-Zaqia, told the AP that his forces had entered and been in control of the compound since last week, a day after it has seized control of the capital and its international airport after weeks of fighting with a rival militia. Abu-Zaqia said the rival militia was in the compound before his troops took it over.

The Dawn of Libya militia is not associated with the extremist militia Ansar al-Shariah, which Washington blames for the deadly assault on the U.S. Consulate in Benghazi on Sept. 11, 2012, that killed Stevens and the three other Americans.

On July 26, U.S. diplomats evacuated the compound and the capital to neighboring Tunisia under a U.S. military escort as fighting between rival militias intensified and thousands fled. The State Department said embassy operations would be suspended until the security situation improved.

Typically, local forces provide security for diplomatic posts, but Libya's government has largely relied on militias for law enforcement since Gadhafi's ouster, as its military and police forces remain weak. In the past several weeks, the security vacuum in Tripoli deepened as militia violence worsened. It remains unclear who the U.S. left in control of guarding its facilities after its personnel evacuated.

Libya's militias, many of which originate from rebel forces that fought Gadhafi, have become powerful players in post-war Libya. Successive governments have put militias on their payroll in return for maintaining order, but rivalries over control and resources have led to fierce fighting among them and posed a constant challenge to the central government and a hoped-for transition to democracy.

Following weeks of fighting that brought the capital to a standstill, the Dawn of Libya militia said last week it managed to seize control of Tripoli's airport and drive a rival militia from the mountain town of Zintan out of the capital. It is now deployed around the capital and has sought to restore normalcy in the city. The group called on foreign diplomats to return now that the fighting has subsided.

Associated Press contributed to this report.