Lebanon's Hezbollah-led opposition supporters have clashed with those backing the government for a second day in Beirut as the confrontation spilled over to other parts of the country.

Army and riot police manned checkpoints and blocked several roads while many schools and businesses in the capital remained shut on Thursday.

The demonstration quickly degenerated into violence, with rival supporters exchanging gunfire.

Members of opposing camps exchanged gunfire in the village of Saadnayel in the eastern Bekaa Valley.

Four people were injured, security officials said.

In Beirut, residents woke up to new demarcation lines, burning tyres and roadblocks.

Some roads remained closed and traffic was light in the Muslim section of the city.

The army deployed armoured carriers on major roads and points of friction in the city. It set up checkpoints and searched vehicles in tense neighborhoods.

Lebanon's international airport was closed because of the anti-government protests.

"All flights between midnight [2100 GMT on Wednesday] and noon were cancelled, and then we will see what happens," an airport official said.

Minimum wage

The strike was originally called by the country's main labour union to push the government to raise the monthly minimum wage which has been unchanged since 1996.

"What is happening today is the start of a disobedience [campaign]," an opposition source said.

"Roads will remain closed, including those leading to the airport, until the government rescinds its decisions."

The government has also accused the Hezbollah of installing spy cameras at Rafiq Hariri International airport and removed the airport's head of security, a figure close to the opposition, from his post.

Hezbollah and Shia political and religious leaders have rejected the government's allegations.

Roadblocks

The industrial action, backed by the opposition, was called by the General Confederation of Labour Union (CGTL).

On the eve of the protest, the cabinet agreed to raise the minimum wage by $130 to $330, but the CGTL said it was insufficient.

The federation is demanding that the minimum wage be increased to $600. The government has refused such a rise, with Jihad Azour, Lebanon's finance minister, saying it could fuel inflation.

A series of roadblocks, many made up of burning tyres and old cars, sprung up in some of the capital's neighbourhoods, enforcing the strike.

Later, explosions and gunfire could be heard throughout the city, but James Bays, Al Jazeera's correspondent in Beirut, said it was not immediately clear who was behind the fighting.

"There was fighting between rival political groups, but all the political parties are saying they didn't order it, they weren't behind it."

He reported there was a strong army presence, but that the armed forces had not been involved in the fighting.

"Their role is to try to bring back calm to the situation - they don't want to be drawn into the fighting and certainly we haven't seen them involved in any of the fighting," he said.

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