BEIRUT, Lebanon - Hezbollah-led opposition protesters blocked streets in central Beirut and on the road to the international airport Wednesday to enforce an anti-government labor strike that has turned into a showdown between the militant Shiite group and Western-backed Prime Minister Fuad Saniora.

Thousands of soldiers and police fanned out in the city and on major highways, deploying armored vehicles at intersections. But security forces largely stayed on the sidelines as the protesters blocked roads with burning tires although they were on alert to prevent any confrontation between pro- and anti-government supporters.

The strike was called by labor unions to demand pay raises after they rejected a last-minute government offer as insufficient, but it came against the backdrop of a confrontation between the government and Hezbollah.

The trouble came as the deep political crisis engulfing Lebanon has worsened economic problems caused by the rising cost of living due to spiraling oil prices and a sharp rise in the euro exchange rate.

But just as the country is divided politically into opposition and pro-government camps, the unions were split as well on whether to support the strike.

Pro-government political groups and labor unions called on people to ignore the strike, while the opposition urged supporters to take part and join a labor demonstration in Beirut later Wednesday.

To enforce the strike, young opposition activists early Wednesday morning began pilling tires and setting them on fire on some major highways in opposition-controlled areas of the city and its southern suburbs.

Trucks brought in dirt and dumped it on the main highway to Beirut international airport and several nearby intersections to block access. In some areas, old cars or garbage containers were brought to the middle of streets and set afire.

In central Beirut, where an opposition sit-in has paralyzed the commercial heart of the capital since December 2006, black smoke rose from burning tires only a few blocks from Saniora's office, where the prime minister has been holed up for about a year and a half.

Labor unions at the country's only airport were taking part in the one-day strike, announcing a six-hour work stoppage starting at midmorning. The strike at the airport was expected to cause the cancelation or delay of 19 incoming and 13 outgoing flights.

The strike was largely confined to Shiite Muslim areas of Beirut and its southern suburbs where support for Hezbollah is strong. The strike was largely ignored in Sunni Muslim and Christian areas of the city which support the government.

However, many schools were closed because the strike halted buses and authorities wanted to avoid putting students at risk on the roads because of possible unrest.

Protesters also blocked highways in southern, northern and central areas of the country to deny motorists' access to Beirut.

Lebanon's political crisis took a turn for the worse earlier in the week when the government decided to confront the powerful Hezbollah.

The Cabinet on Tuesday decided to remove Beirut airport's security chief over alleged ties to Hezbollah. The government also declared that a telecommunications network used by Hezbollah for military purposes was illegal and a danger to state security.

Hezbollah and Shiite political and religious leaders rejected the government's decisions. Shiite ministers have been boycotting Cabinet meetings since 2006.

Hezbollah is listed as a terrorist group by the United States and fought Israel in the 2006 war. It has wide support among Shiites in Lebanon, but its backing among the rest of the population has been declining because of its opposition to the government and Shiite-Sunni tensions.

The government maintains the armed group cannot set up a state-within-a-state, while Hezbollah accuses Saniora and his supporters of colluding with the United States in trying to crack down on the guerrilla group and disarm it.

Lebanon's top prosecutor began investigating allegations that Hezbollah set up cameras near the airport in the Hezbollah strongholds of south Beirut to monitor the movement of anti-Syrian Lebanese politicians and foreign dignitaries.

The allegations were made by anti-Syrian, pro-government leader Walid Jumblatt, who has accused Hezbollah of placing the cameras. Jumblatt suggested Hezbollah was planning to bomb aircraft to assassinate senior leaders. -AP