Three days into a strike, Portuguese fuel tanker drivers have rejected a new government decree requiring them to fulfil minimum services or face arrest or even jail.
"No-one will respect the minimum service or civil requisition," said union spokesman Pedro Pardal Henriques.
Strikers reacted angrily after proceedings began against 14 drivers who did not comply with the decree.
The government is trying to stop the strike hitting key tourist areas.
Officials are particularly keen to protect Lisbon airport and the southern Algarve coastal region and the military and police have been drafted in to help move fuel stocks to areas that are running dry.
Petrol rationing has already begun and the government's decree is aimed at keeping basic services running. Ministers are insisting that half of normal deliveries reach petrol stations and 75% for public transport.
One Portuguese crowd-sourcing website reported that 437 petrol stations out of a total of 3,003 were without any sort of fuel on Wednesday. Goods transport association Antram warned that any attempt to ignore the minimum service decree could seriously harm the economy.
Environment Minister Joao Pedro Matos Fernandes said on Tuesday evening that 14 drivers were being notified of carrying out a crime of disobedience.
In theory, anyone breaching the "civil requisition" could face up to two years in jail and one union official, Manuel Mendes, acknowledged that some drivers were boycotting the minimum service requirement.
He said some drivers had been threatened with dismissal if they did not respect the decree.
"We have to stop this joke. We have drivers threatened with arrest and prosecution," Mr Mendes told the Observador website.
According to local reports, 71 fuel tankers had left the Aveiras de Cima depot in Lisbon on Wednesday. Trucks were also seen leaving a refinery at Matosinhos near Porto, with the aim of transporting fuel to the north.
At Sines in the south, union official Carlos Bonito was quoted by the Lusa news agency as saying that minimum services would be fulfilled on Wednesday, as they had the previous day.
Government officials said that police and soldiers had also helped transport 28 tankers in the first two days of the strike.
The unions are seeking staged increases in their basic salaries and improved working conditions.