Protesters blocked roads with blazing tyres in the Lebanese capital and disrupted air traffic during a general strike on Wednesday that escalated into a confrontation between rival political camps.

Anti-riot police and the army were out in full force, cutting off access to many areas with road blocks to prevent clashes between supporters of the Hezbollah-led opposition and the Western-backed government.

Youths set tyres and cars on fire and overturning rubbish bins near Beirut international airport, where flights have been cancelled for several hours.

Hezbollah operatives brought in trucks loaded with dirt and dumped it on the airport road in the southern suburbs of Beirut which are largely controlled by the powerful Shiite Muslim militant group.

A security official told AFP a grenade was thrown in the seafront Corniche al-Mazraa district of the capital, slightly injuring two soldiers and three civilians.

AFP correspondents saw masked youths throwing stones in the area as supporters from rival camps faced off, screaming insults at each other as army troops stood between them.

An airport official told AFP that although several flights flew in and out of the airport in the early morning, flights were cancelled between 9.00 am and 3.00 pm.

Many schools and businesses shut down but it was business as usual in many areas not affected by the strike.

A demonstration due to be staged in Beirut by the country's main labour union was cancelled as few people were able to reach the main gathering point.

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

Although the cabinet on Tuesday agreed to a $130 increase a month to $330, the General Confederation of Labour Unions said it was insufficient.

The federation is demanding that the minimum wage be increased to $600 but the government has balked at such a rise, and Finance Minister Jihad Azour has said it could lead to rampant inflation.

But some lamented the fact that the strike was being hijacked by the pro- and anti-Syrian camps and that the wage demands would fall by the wayside.

"More detrimental to us than the economic situation"

"What they are doing is more detrimental to us than the economic situation," said hairdresser Lina Abu-Ziki (35), commenting on the youths.

In the southern coastal city of Tyre, hundreds gathered in the main square demanding the resignation of Prime Minister Fuad Siniora. Similar protests were held in other major towns.

Wednesday's strike action comes amid a backdrop of mounting tensions between the ruling Western-backed coalition and the opposition, which have been locked in a power struggle for 16 months.

The political crisis, the worst since the end of the 15-year civil war in 1990, has prevented the election of a president since November, when pro-Syrian Emile Lahoud stepped down at the end of his mandate.

The crisis is widely seen as an extension of the confrontation pitting the United States and its Arab allies against Syria and Iran.

On Tuesday, tensions rose even further after the government announced it was launching a judicial probe into a telecommunication network that Hezbollah has set up across the country with the alleged help of Iran.

The cabinet also decided to dismiss the head of airport security amid allegations he was aware that Hezbollah had set up surveillance cameras overlooking an airport runway.

AFP