Italy's striking truck drivers used hundreds of vehicles to block highways outside large cities and border points Tuesday, causing shortages of gasoline and perishable food.

The strike forced Fiat to lay off thousands of workers temporarily for lack of supplies at factories.

Most of Italy's supplies move on wheels. But little fuel was delivered to pumps on the second day of a five-day strike to press demands for lower gasoline prices and shorter working hours.

Unions walked out of a meeting Tuesday with Transport Minister Alessandro Bianchi, breaking off negotiations meant to end the strike.

Trucks blocked traffic on highways outside Rome, Milan and other major cities. Many gas stations across Rome were closed or put up signs reading "out of fuel." Long lines of cars and scooters formed in front of those still operating.

Fiat Group said more than 22,000 employees were temporarily laid off as of Tuesday afternoon. The number "is expected to grow in the next few days and involve all the 50,000 workers of the manufacturing areas," Italy's largest private-sector company said in a statement.

The group, which includes the Fiat automaker, said the strike was "drastically reducing the competitiveness of our country."

Rotting produce was all that was left on many supermarket shelves. Fresh meat, milk, fruit and vegetables were scarce.

"Since yesterday we haven't had any deliveries," said Ruggero Giannini, sales manager at a supermarket in downtown Rome. "We are powerless in the face of such a situation."

The Italian farm lobby Coldiretti said farmers would lose millions of dollars if tons of perishable goods remain undelivered. The distribution of animal feed was also threatened, a statement from the group said.

Gasoline station associations said about 60 percent of the pumps in the country had been idled, and most of those still operating would be forced to shut down by Tuesday evening.

"The supply problem is causing a real paralysis," said Luca Squeri, head of the FIGISC gas station federation.

Italian news reports said some drivers who refused to join the strike were attacked, and some of their vehicles were stoned and had tires slashed.

Although the walkout had been announced, the authority that monitors strikes in Italy said that blocking traffic and essential supplies was unlawful and urged the Transport Ministry to order the drivers to return to work.