Forces fighting to oust the Libyan leader Col Muammar Gaddafi have seized the city of Zawiya, 50km (30 miles) west of the capital, Tripoli.

The Libyan government took journalists to Zawiya on Sunday morning.

But instead of a show of government force, reporters saw opposition fighters manning the barricades in the city centre and flying their flag.

The UN Security Council voted unanimously on Saturday to impose sanctions on Col Gaddafi's regime.

Eastern Libya has fallen to the uprising, which began on 16 February in the wake of revolutions which toppled the long-serving leaders of neighbouring Tunisia and Egypt.

However the Libyan capital Tripoli remains under the control of Col Gaddafi, who is facing the biggest challenge to his 41-year rule.

At least 1,000 people are believed to have been killed in nearly two weeks of violence.

The UN refugee agency (UNHCR) says nearly 100,000 migrants have fled to neighbouring Tunisia and Egypt in the past week.

It warns of a growing humanitarian crisis. Many of the migrants have no way to get home and are sleeping out in the open.
'Ready to fight'

Pro-Gaddafi forces are surrounding Zawiya, which saw fierce fighting last week.

BBC Middle East editor Jeremy Bowen, who was on the government-organised trip to Zawiya, says the centre of the city and its immediate outskirts appear to be wholly in the control of anti-Gaddafi forces.

Pro-Gaddafi forces have tried a couple of times to enter the city, local people have told him, but the rebellion has been going on since 17 February, and they say it is going to continue.

I spoke to doctors, to a lawyer, to various police officers who have changed sides - there were soldiers there who changed sides as well - and they're running (Zawiya) as a sort of people's republic in the centre of the town.

Some people are saying that the town is split. They're saying there may even be a protest rally in favour of Gaddafi. We await that with interest.

But certainly the people in the centre of town - at least a couple of thousand - were damant they were not going to budge.

Some of the demonstrators in central Zawiya fired weapons into the air, saying they were protesting peacefully but were ready to fight.

"This is our revolution," some, quoted by Reuters news agency, chanted.

A number of protesters stood on top of a captured tank while others crowded around an anti-aircraft gun, Reuters added.

In a televised speech on Thursday, Col Gaddafi addressed the people of Zawiya, saying young people were being duped with drugs and alcohol to take part in "destruction and sabotage".

The BBC's Firas Kilani in Tripoli says the situation in the capital is calm, and hundreds of people are gathered in front of banks to receive cash the Libyan leader recently granted to each family.

The Security Council unanimously backed an arms embargo and asset freeze on the Libyan government. It also voted to refer Col Gaddafi to the International Criminal Court for alleged crimes against humanity.

Col Gaddafi's son Saif al-Islam denied that the leader had any assets abroad.

"We are a very modest family and everybody knows that," he told ABC News. "They are saying we have money in Europe or Switzerland... It's a joke."

John Simpson: "Small towns are liberating themselves against fighting"

He also commented on the senior government officials and diplomats who have joined the anti-government camp, calling them "hypocrites".

"It's good we get rid of them," he said.

US President Barack Obama has said the Libyan leader should step down and leave the country immediately.

Italy - which has close ties to Libya - said on Sunday that the end of Col Gaddafi's rule was "inevitable".

Italian Foreign Minister Franco Frattini also said a friendship and co-operation treaty between the two countries was "de facto suspended".

Discussions on forming an anti-Gaddafi transitional government are reportedly under way in Libya.

Mustafa Abdel-Jalil - who resigned as justice minister in protest against the excessive use of force against demonstrators - said a body comprising military and civilian figures would prepare for elections within three months, Libya's privately-owned Quryna newspaper reported.