Attackers bulldozed a Sufi Muslim shrine and mosque in the Libyan capital on Saturday, one day after hardliners razed a similar shrine and library elsewhere in the country.

It was not immediately clear who was behind Saturday's attack, the third on a Sufi shrine in Tripoli in recent months, although officials have blamed past vandalism on Islamic hardliners, some of whom are followers of the ultraconservative Salafi doctrine.

Libya is a deeply conservative Muslim nation, and Islamists were heavily repressed under longtime dictator Moammar Gadhafi, who was captured and killed in October after an eight-month civil war. Since then, there has been a string of attacks on shrines across the country belonging to Muslim sects.

The campaign appears to be aimed mainly at shrines revered by Sufis, a mystical order whose members often pray over the tombs of revered saints and ask for blessings or intervention to bring success, marriage or other desired outcomes. Hard-line Salafi Muslims deem the practice offensive because they consider worshipping over graves to be idolatry.

Libya's Grand Mufti, Sheik Sadek al-Ghariani, condemned the vandalism and said it was the government's responsibility to protect the graves.

"No group outside of the government should use weapons and it is the responsibility of the government to provide security and prevent religious strife and division," he said in a statement Saturday.

Resident Abdullah Zakaria said he saw the bulldozers destroy the Sufi tombs Saturday morning. Hours later a group of men bulldozed a mosque in the same area that also contained tombs.

Security officials closed the road leading to the shrines and mosque but did not intervene to stop the men from attacking the mosque hours later. Police were seen instead protecting a nearby hotel.

Interim President Mohammed el-Megarif said in a televised speech Saturday called the actions "unacceptable" and vowed the perpetrators would be prosecuted. He also called on citizens and the security services to be more vigilant in preventing disruptive behavior.

Following the civil war, Libya has been largely without a military or police force and has relied on disparate militias to provide security and protect government installations.

Libyan writer Fathi Bin Eissa, a Sufi, said he had hoped the police would investigate who ordered past desecration of the shrines and wanted answers as to why security forces moved to protect the hotel, but did nothing as the mosque was being bulldozed before their eyes.

A security official said the police were ordered only to ensure violence does not break out.

Other attacks have taken place in the past against shrines in the eastern cities of Darna and Benghazi.

More recently, extremists on Friday bulldozed one of Libya's most important Sufi shrines and Sufi libraries in the city of Zlitan, 90 miles (145 kilometers) southeast of Tripoli.

Security officials say the attackers took advantage of deadly clashes between tribes in Zlitan this week to attack the more than 500-year-old shrine and library.

All officials spoke on condition of anonymity because they were not authorized to release the information.