China's crude imports from Russia in July plunged 45 percent from a year earlier to 615,193 tonnes, or 144,870 barrels per day (bpd), the lowest level in several years, customs data showed on Monday.

That pushed Russia into ninth place among crude oil suppliers in July, with Saudi Arabia selling more than six times as much, followed by Iran and Angola in second and third place.

However, traders had suspicions about the accuracy of the customs data, saying it was impossible that crude imports from Russia fell that low after the start of the Russia-China crude pipeline.

Russia has started crude oil exports to China via a new spur of the Siberian ESPO pipeline since January, which is scheduled to transport 300,000 bpd of crude to northeast China.

Besides oil imported via the pipeline, state oil traders Unipec and Sinochem have also imported several Russia ESPO and Vityaz crudes for July arrival via shipments, the traders said.

If you count three or four cargoes of ESPO and Vityaz crudes shipped by Sinochem and Unipec, July imports via the pipeline were even lower, said a crude trader.

Oil major PetroChina , buyer of ESPO crude via the pipeline and operator of China's part of the pipeline, said the pipeline is running normally.

I have not heard anything unusual on the operation of the China-Russia oil pipeline, said Mao Zefeng, head of PetroChina's investment relations.

Crude imports from Russia in the January-July period slid 4 percent year on year to 9.42 million tonnes, or 324,420 bpd, the customs data showed.

Imports of crude oil from the northeastern Manzhouli port has stopped since February, indicating Russian oil major Rosneft has abandoned its traditional railway crude supplies as the flow through the pipeline cranked up.