China has increased U.S. crude purchases with some buyers snapping up cargoes at the widest discounts ever as sellers seek to offload excess supplies in Asia, six trade sources said on Wednesday.

Beijing started processing in March applications from Chinese companies to waive import tariffs on U.S. energy goods as part of the Sino-U.S. Phase 1 trade deal and they have since bought liquefied natural gas (LNG) and liquefied petroleum gas (LPG) from the United States.

The world's largest crude importer is boosting U.S. energy imports at a time when the world is swamped with excess supply after the Organization of the Petroleum Exporting Countries (OPEC) and Russia failed to extend production cuts and as measures to curb the spread of the coronavirus destroyed demand.

Cheap U.S. energy supplies will help China lower its import costs, but the deep discounts will add further pressure on U.S. producers to shut in production after U.S. crude futures slumped to their lowest since 2002.

U.S. Mars Sour crude has been sold to Chinese buyers at discounts between $7 and $9 a barrel to September ICE Brent futures for July arrival while the discounts for West Texas Intermediate crude (WTI) in Midland were between $6 and $7 a barrel, the sources told Reuters.

BP and Equinor may have sold some of these cargoes, they said, while the buyers were not immediately known. BP declined to comment while Equinor could not be immediately reached for comment outside office hours.

"Only the Chinese are buying and the rest of the world are selling," a Singapore-based trader said, leading to some "very aggressive offers" for U.S. crude into that market even though the oil's benchmark is already at the lowest in 18 years.