The Venezuelan Government has commandeered and steered into port an oil tanker in an attempt to break a general strike that has led to severe petrol shortages.

The ship, the Pilin Leon, sailed into port in Lake Maracaibo on Saturday and began unloading its cargo of petrol.

Motorists wait hours to fill up

The ship had become emblematic for the opposition, after its captain joined the strike and moored offshore, refusing to dock.

The move comes as opponents of President Hugo Chavez took part in another march in the capital, Caracas, to demand early elections.

The 20-day-old strike has crippled oil production in Venezuela - the world's fifth largest exporter of crude.

On Friday, government forces boarded the Pilin Leon and detained its crew.

On Saturday strike-breaking workers took the ship to the oil terminal of Bajo Grande.

'Victory'

Local media say distribution to petrol stations in western Venezuela should take place over the next two days.

The opposition demonstrated in support of the Caracas police force

The chairman of Venezuela's state oil company, PDVSA, has described this as a victory for the government

The chairman, Ali Rodriguez, said the authorities would shortly move other striking tankers.

Petrol shortages have forced many stations to close. On Saturday there were queues at those that were open in the Caracas area.

The growing unavailability of petrol has sparked fears of food shortages and civil unrest.

Mr Chavez has denounced PDVSA executives - many of whom have joined the strikers - as "coup-plotting oil elites" and said he would "clean up" the company.

On Wednesday the president issued a decree allowing the military to commandeer privately-owned lorries, ships and planes to distribute supplies.

Warning

On Saturday, hundreds of anti-government protesters took part in a march in Caracas celebrating the 33rd anniversary of the city's police force.

Mr Chavez denounced "coup-plotting oil elites"

The protesters waved Venezuelan flags and held banners demanding the resignation of Mr Chavez.

President Chavez took control of the police force last month, arguing that it was not loyal to the government.

But on Wednesday, the Supreme Court returned authority over the force to the opposition mayor of Caracas, Alfredo Pena.

The opposition accuses President Chavez of mismanaging the economy and authoritarianism, and is calling for early elections.

The threat of widespread unrest has led the UK government to advised its nationals to leave Venezuela.

Families of British diplomats and non-essential members of staff will be withdrawn.

On Saturday Foreign Office spokesman in London said the fuel shortages were "likely to impact on critical supplies of essential commodities in coming days and might in turn trigger disturbances".

Several other countries - the US, Canada and Germany - have already given similar travel advice to their residents.