Hundreds of truck drivers parked their vehicles along key sections of the national road network on the outskirts of Athens and Thessaloniki for a fifth day yesterday, causing traffic chaos as they pushed on with protests against the government's plans to open up their sector to competition. Fears of possible fuel shortages at gas stations were renewed as unionists representing the truckers said they would extend their action into next week when a draft bill foreseeing the liberalization of their sector is to be submitted to Parliament's plenary session in order to be voted into law. The bill was approved by a parliamentary committee on Thursday following several days of debate involving unionists who had objected to the reforms, claiming that they would destroy thousands of livelihoods. Fuel truck drivers, who up until late last night had not participated in the action in order to avert fuel shortages at gas stations, were yesterday considering joining in, sources said. If the fuel truck drivers make good on their threat, motorists might face the same problem they did in late July when an extended strike by truckers led gas stations to run out of fuel. According to some sources, the truck drivers are planning to attempt to force the government's hand by suspending deliveries of fuel and other goods to ports and airports, a move that could lead to transport disruptions later in the week. Some truckers are also said to be considering obstructing trucks belonging to private firms from delivering fuel and goods so that the shortages become acute and the government takes notice. Police have been ordered to continue barring the truckers from entering central Athens, which they tried to do several times this week, but to avoid fueling tensions.