A hauliers' strike against the high cost of fuel continued hurting the Spanish economy on Thursday, with car factories halting production, farmers throwing away milk supplies and shops running short on foodstuffs, according to dpa. Distribution to wholesale markets was, however, improving in some regions, such as north-eastern Catalonia, as police escorted transport lorries to protect them from pickets. Prime Minister Jose Luis Rodriguez Zapatero pledged to take the necessary measures to keep traffic moving normally and said the government would have "zero tolerance" towards acts of coercion or violence. Car factories lacking for parts halted the production of thousands of cars in stoppages affecting thousands of workers around the country. Fruit and vegetables were rotting at southern production sites, with producers estimating their losses at 100 million euros (150 million dollars) so far. Dairy farmers threw away milk supplies. They and other livestock farmers unable to feed their animals or to take them to slaughterhouses estimated their losses at 45 million euros. Markets running short on fresh fruit, vegetables, fish and poultry raised their prices in Madrid, media reported. Containers also accumulated at ports, but the situation was gradually improving as the deployment of 25,000 police was helping traffic return to normal. Traffic to France was moving smoothly after blockades were lifted at the border posts of Irun and La Jonquera. Hundreds of trucks, however, remained on the Portuguese border for fear of being stopped by protesters in Spain or France. Five pickets were detained on charges of setting vehicles on fire or puncturing tyres. A total of nearly 100 truck drivers have been arrested since the beginning of the strike, the Interior Ministry said. Hauliers' associations representing less than 20 per cent of the sector's workforce are continuing their strike for the fourth day after refusing to join an agreement between the government and other associations on 54 measures to alleviate the impact of fuel prices. The strikers want a minimum rate level for their services, which the government rejects as violating European Union legislation. Hauliers meanwhile ended their strike in neighbouring Portugal after reaching a preliminary agreement with the government. The government had shown "a clear and unequivocal will to solve the problem" of fuel prices in Wednesday's negotiations, hauliers' representative Antonio Loios said. The planned measures included postponed VAT payments and lower road tolls. Pickets were demobilized after the three-day strike which had led to shortages at supermarkets. Hundreds of petrol stations had run out of stocks, and Lisbon airport prohibited most planes from refuelling on Wednesday. The strikes have claimed the lives of two pickets who were hit by trucks in Spain and Portugal.