Libyans attend the funeral of people killed in air strikes by coalition forces last night, at the martyrs' cemetery in Tripoli on Saturday. Louafi Larbi/Reuters

Mourners vowed revenge and rattled off heavy gunfire in a Tripoli cemetery on Saturday as they buried nine men they said were Muslim clerics and medics killed in a NATO airstrike in mostly rebel-held eastern Libya.

The Libyan government took it upon itself to announce the time and place of the funeral on state TV and over text messages. A few hundred men showed up and at least a dozen were soldiers.

NATO has been intensifying airstrikes against Gadhafi's troops in several areas of Libya in a bid to weaken his brutal crackdown against a rebel uprising.

The sound of another apparent NATO airstrike was heard in Tripoli on Saturday night. Libyan state TV said it targeted a site at the Bab al-Aziziya military base that includes Gadhafi's residence

A NATO official in Naples said warplanes targeted a military command and control site and that she was "aware of reports" of civilian deaths in the Brega attack, but "we cannot independently verify that."

Libyan government spokesman Moussa Ibrahim said the men killed early Friday were clerics who met in the port town of Brega, which has been fought over throughout the three-month conflict, to pray for peace. Ibrahim said dozens of clerics hoped to head to the rebel-held eastern part of Libya to seek an end to the war

He said 11 people were killed and added that 50 people also were wounded, including five in critical condition.

A cleric who identified himself as a witness gave a different account and said only nine were killed. He said they were a group of 16 men sent by the country's Islamic affairs department to Brega to demonstrate that the port city was firmly in the hands of Gadhafi's forces as an act of defiance.

"We wanted to show that Brega wasn't in rebel hands," the cleric said. The cleric said three strikes hit their guest house and confirmed that one of the dead was a leading cleric named Sheik Omar Ibrahim

In a statement Saturday, NATO said the building struck in Brega had been "clearly identified as a command and control centre." It said it could not confirm civilian deaths.

Greece to liaise with rebels

Meanwhile, Greece says it will send diplomats next week to the Benghazi to act as liaisons with rebels, while also maintaining relations with Tripoli.

Foreign Minister Dimitris Droutsas says "Greece's role is to talk and have a dialogue with all sides in this crisis." He made the comments to reporters Saturday after talks with U.N. envoy to Libya Abdul Ilah Khatib.

Khatib, a former Jordanian foreign minister, will travel to Tripoli on Sunday aboard a Greek air force plane. It will be hisseventh trip to Libya since the NATO air strikes began in late March.