The oil conglomerate PTT Plc temporarily suspended oil and gas depot deliveries yesterday morning to prevent attacks, according to Dr Prajya Phinyawat, senior executive vice-president.

The main oil and gas depots including those of Bangchak and Thai Petroleum Pipeline are shut down for now.

“We are not sure that trucks carrying gas and oil won’t be seized by demonstrators until the riots in inner city calm down,” said Dr Prajya.

Global positioning systems installed in each truck will be carefully checked.

Officials were monitoring all travel activities from the time trucks left the depots and destinations were also being tracked.

Seventy service stations were ordered closed in high-risk areas yesterday.

Motorists could refill vehicles at service stations on the outskirts of Bangkok.

Meanwhile the Electricity Generating Authority of Thailand has raised its alert to higher security, said governor Sutat Patmasiriwat.

Egat has barred outsiders from entering to its power plants nationwide, some of which are normally open for tours, The state utility has also set up a special security team to ensure safety around the clock for the main transmission lines across Greater Bangkok.

“The team will work as an emergency unit to fix the line if there is any disruption to the electricity system,” said Mr Sutat.

“We are also prepared a stand by power generator to be ready to start up as soon as possible if the situation gets worse.”