A seized Italian tugboat and its crew left the Libyan port of Tripoli todayaccompanied by people claiming to represent port authority and Libyan military officials, a statement by the ship's owner said.

The 11 crew members "are fine and are on board the ship", said Augusta Offshore, a company based in the southern Italian port of Naples that specialises in assisting oil rigs as well as exploration and production activities.

"We are in constant contact with the foreign ministry's crisis unit to cooperate and we are coordinating with the authorities," it said.

The ship's crew is made up of eight Italians, two Indians and a Ukrainian national.

Italian Defence Minister Ignazio La Russa said earlier today that Rome was ready to use "all possible means" to free the crew of the high-seas tugboat.

"We are on standby for an evacuation of the detained tugboat crew by all possible means," he told Rai 3 television.

Armed men, including one who claimed to be the harbour master, detained the crew and were holding them on board the 75-metre ship, officials and media reports said.

"This is a delicate situation which the harbour master's office and the foreign ministry are monitoring. When they ask us to intervene, we will do so, but that does not depend solely on the defence ministry," La Russa said.

Foreign Minister Franco Frattini said it was unclear why the men had been seized but that Rome did not rule out a kidnapping.

"We don't know what are the intentions" of the men who seized the 11 crew members yesterday, but "we cannot exclude a kidnapping", the minister said during a telephone call to an Italian television programme.

The ANSA news agency quoted sources as saying the action occurred Saturday afternoon shortly before French warplanes launched air strikes at the start of a Western military operation against Libyan strongman Muammar Gaddafi's forces.

The tugboat was discharging Libyan employees of the Libyan oil firm NOC at the time.