Buses, trucks and motorcycles wait for diesel at a gas station in Langzhong, Sichuan province, on Thursday. Provided to China Daily

China's diesel shortage has paralyzed traffic on a pivotal expressway in northwest China, with trucks waiting in long queues to fill their fuel tanks.

Truck driver Zhang Manku said he waited for eight hours Thursday to fill up at a gas station in Ningqiang, a city in Shaanxi Province close to Sichuan Province.

"I drove into Shaanxi from Sichuan on the Hanning(Hanzhong-Ningqiang) Expressway at 9 a.m., and crept along as part of a 20-km queue of trucks. It was 5 p.m. when it was my turn."

Gao Xiang, an official with the expressway administration, said more than 1,000 trucks were stranded at the Shaanxi/Sichuan border Thursday. "Dozens of road workers were mobilized to divert traffic."

Congestion eased slightly Friday, but most trucks still had to wait at least two hours for diesel, he said.

Gao said the congestion will persist over coming weeks unless the diesel shortage problem is solved.

Sinopec, China's major oil refiner, supplies 100 tonnes of diesel daily to Ningqiang City. "So many vehicles are waiting that we have a limit on each truck," said Dui Jinyu, a sales manager at Sinopec's Shaanxi branch.

He said the company was trying to increase diesel supplies and promised no price hike. "We'll give priority to buses, as well as trucks that transport vegetables, fruits, live pigs and other agricultural products closely related to daily life."

To ease the shortage, Sinopec has promised to increase daily processing of crude oil. It will process 4.27 million barrels per day this month, up 9.9 percent year on year and 1 percent from October.

Some of its oil refineries have also cut output of petrol and industrial chemicals to make room for additional diesel refining.

The company said it would also import 200,000 tonnes of diesel to supplement supplies in some regions.

The unprecedented diesel shortage has closed down many gas stations, and trucks can be seen lining up to buy diesel in many cities.

Experts blame the shortage partly on the "blackout policy" adopted by some local governments to meet their emission reduction goals, as factories hoard diesel supplies to generate electricity to allow them to continue production.