Supporters of Lebanon's government fought gun battles in Beirut on Wednesday with gunmen loyal to the Hezbollah-led opposition, escalating the country's worst internal crisis since the 1975-90 civil war.

Supporters of Iranian-backed Hezbollah blocked main roads in the Lebanese capital with blazing tires, old cars and heaps of earth, paralyzing the city and cutting routes to its sea and air ports.

An opposition source said the protest campaign, including road blocks, would be extended until the government rescinded decisions taken on Tuesday affecting Hezbollah.

The government had pledged to take steps against a private telecommunications network operated by the group and accused it of installing spy cameras at Beirut airport. The cabinet also removed the airport's head of security, a figure close to the opposition, from his post.

Hezbollah has led a 17-month-long political campaign against Prime Minister Fouad Siniora's anti-Syrian cabinet. The conflict has already led to bouts of lethal violence.

Security sources said pro-government supporters exchanged assault rifle and grenade fire with Hezbollah sympathizers in the Beirut neighborhoods of Noueiri, Ras al Nabae and Wata al-Musaitbeh. It was not clear if there were casualties.

Opposition gunmen took over an office of the Future political group led by Saad al-Hariri, leader of the governing coalition, Lebanon's most influential Sunni politician and a close ally of Saudi Arabia.

Youths loyal to the rival sides pelted each other with stones in Mazraa -- one of the Beirut districts where sectarian tensions have been high between Sunnis and Shi'ites.

The army, mostly seen as neutral during the crisis, deployed in force but did not attempt to remove the road barricades.

Government minister Marwan Hamadeh said Hezbollah, a political group with a powerful guerrilla army, was "trying to use military means to block the airport". "Lebanon has said it will not become an Iranian satellite," he told Reuters.

A security source said the army had detained two men armed with M-16 assault rifles in Beirut.

Tension between the government and Hezbollah escalated sharply on Tuesday when the cabinet said the group's communication network was "an attack on the sovereignty of the state". Hezbollah said it was part of its security apparatus and played a major role in its war with Israel in 2006.

"Armed and angry"

Provoked by the government's moves, Hezbollah was "flexing its muscles" in the streets, said Oussama Safa, director of the Lebanese Center for Policy Studies. "The heat has been turned up," he said, adding that there was scope for violence.

"But it's probably not going to unfold into war. A confrontation is not winnable," he said.

"Things could get very ugly, but I don't think they will spread out of hand," added Paul Salem, director of the Carnegie Middle East Center in Beirut. "Everyone is armed and angry."

Hezbollah was the only Lebanese faction allowed to keep its weapons after the civil war to fight Israeli forces occupying the south. Israel withdrew in 2000 and the fate of Hezbollah's weapons is at the heart of the political crisis.

A U.N. Security Council resolution that ended the 2006 war between Hezbollah and Israel bans the group from rearming and rebuilding its military infrastructure in south Lebanon.

Governing coalition leaders allege Hezbollah is spying on the airport to monitor their movements. Eight members of the anti-Syrian coalition have been assassinated since 2005.

Hezbollah has deemed Siniora's cabinet illegitimate since its Shi'ite ministers resigned in 2006. The governing coalition has refused to yield to the opposition's demand for effective veto power in cabinet. The crisis has paralysed much of government and left Lebanon without a president for five months.

Air traffic was suspended for six hours on Wednesday because of a strike by staff taking part in labor union action to demand more pay. The opposition had urged its supporters to back the strike.

PHOTO CAPTION:

Riot in Lebanon

Rueters