"My company will take full responsibility to guarantee sufficient diesel supply to local users," said added the Sinopec Shanghai Oil Products executive, identified only as Wang.

Although already responsible for about 70% of the city's refined oil market, disruption of supplies to its biggest rival - PetroChina Co - and to many other private fuel stations has added further demand for Sinopec Shanghai's fuel supply. Wang confirmed that the loss of supply to its rivals "switched pressure to Sinopec's stations".

The situation has not been helped with the increase in prices for diesel fuel in the neighbouring provinces of Jiangsu and Zhejiang, which has forced many buses and truck companies choosing to tank up in Shanghai where prices remain relatively unchanged.