Tear gas and gunshots are reported as pro-Gaddafi forces clash with protesters in Tripoli, while witnesses say dozens have been killed in a city held by rebels.

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Gunshots were heard in the Libyan capital as anti-government demonstrators shouting "Gaddafi is the enemy of God" clashed with security forces.

Following the weekly Friday prayers several hundred demonstrators took to the streets in the in the eastern district of Tripoli chanting for an end to Gaddafi's 40 years in power.

They were met by pro-Gaddafi security forces in military fatigues and with green scarves around their heads.

"They fired tear gas. I heard shooting. People are scattering," a witness said.

A convoy of 14 vehicles with security forces on board reportedly sped through a checkpoint towards the site of the protest in the Tajoura district.

Abdullah al-Mahdi, a spokesman with anti-government protesters, told Al Jazeera television that opposition fighters would attack the capital once a "no-fly" zone was enforced by international powers to try to shatter Gaddafi's grip on Libya.

'30 dead'

Rebels holding the port city of Zawiyah, 30 miles (50 km) west of Tripoli said they had launched counter-attacks against Gaddafi's forces massing in the area and warned supplies of medicines and baby milk were running low.

According to reports, at least 30 people have been killed in the city on Friday, with many more wounded. A witness at the scene said a local hospital was "full" of civilians killed in violent clashes. The number of casualties was expected to rise, a witness said.

Among the dead was the town's rebel commander, residents said.

A government spokesman said Gaddafi security forces expected to regain control of rebel-held Zawiyah.

There was also fierce fighting at the port city of Ras Lanuf, in the east of the country, which rebels attempted to seize. Government forces were reported to have launched an aerial bombardment of the city.

International action

Interpol has issued a worldwide alert for Colonel Gaddafi and 15 of his closest associates as individuals who have been identified "as being invollved in or complicit in planning attacks, including aerial bombardments, on civilian populations".

Britain and a number of other nations are considering various options, including the imposition of a no-fly zone, but are wary about any offensive military involvement to stabilise the world's 12th-largest oil exporter.

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Libya: Shots fired at protests as money ship seized

US President Barack Obama said he was concerned that a bloody stalemate could develop between Gaddafi and rebel forces, but gave no sign of a willingness to intervene militarily.

"Muammar Gaddafi has lost the legitimacy to lead and he must leave," Obama said.

The upheaval is causing a humanitarian crisis, especially on the Tunisian border where tens of thousands of foreign workers have fled to safety. But an organised international airlift started to relieve the human flood from Libya as word spread to refugees that planes were taking them home.

Money ship seized

In Britain, officials seized a ship reportedly carrying £100m of Libyan money and escorted it to port, the Home Office said.

The vessel returned to UK waters after failing to dock in the Libyan capital Tripoli last weekend.

The UK Border Agency said the ship was tracked and intercepted off the UK coast before being escorted into Harwich docks in Essex .

"A number of containers were offloaded from the boat and have been taken under control of UK Border Agency and have been moved to a secure location," a Home Office spokesman said.

"The cargo is understood to contain a significant quantity of Libyan currency, which is subject to a UN sanction."

The Government imposed an export control order banning any Libyan currency leaving the country for the next year. The dinar is printed in a warehouse in north-east England.

It is understood the unnamed ship failed to berth in Tripoli last weekend because her crew believed it was too dangerous.

Reports suggested the cargo ship was carrying £100m worth of the Libyan currency, but the Home Office refused to confirm the exact value.