The rapid increase of domestic diesel prices to nearly 33 baht a litre is pushing the Land Transport Federation of Thailand (LTFT) to prepare to petition Prime Minister Srettha Thavisin next Tuesday to cut the price back to 30 baht a litre.
LTFT representatives plan to meet Mr Srettha during his weekly cabinet meeting on June 11 as the surge in diesel prices adds a huge financial burden to goods transport operators.
The retail price of diesel soared by three baht in one month to 32.94 baht a litre on May 31, according to the federation.
"We are able to raise transport prices for new customers, but we must uphold the prices stipulated in agreements with existing customers. To adjust transport prices for the latter group, we must negotiate," said Thongyoo Kongkhan, advisory chairman of the LTFT.
The LTFT wants the government to consider cutting diesel prices because an increase of diesel prices by one baht a litre means operating costs rise by 3-5%.
"This is not the time to increase transport prices, given the ongoing economic slowdown," said Mr Thongyoo.
The economy has eased this year, with GDP growth rising only 1.5% year-on-year in the first quarter, according to the National Economic and Social Development Council.
The cabinet resolved in April to end the diesel price ceiling policy of 30 baht a litre, following the expiry of the diesel excise tax cut of one baht a litre on April 19.
Authorities agreed to let retail diesel prices gradually rise to 33 baht a litre, effective from April 20 to July 31. Officials are subsidising diesel prices through the loss-ridden state Oil Fuel Fund.
As of May 26, the fund posted a total loss of 111 billion baht, resulting from diesel price subsidies of 63.7 billion baht and subsidies for liquefied petroleum gas (LPG), which is used as cooking gas, of 47.7 billion baht.
"We cannot solely attribute the blame to goods transport trucks, as LPG is also used as vehicle fuel by households," he said.