At 02:30 GMT the front-month June WTI Nymex crude futures contract was at $30.77/bl, up by $1.34/bl from its close on 15 May. Nymex WTI crude futures last settled above $30/bl on 13 March.
The Ice front-month July Brent contract was at $33.78/bl, higher by $1.28/bl from its settlement on 15 May.
The imminent expiry of the June WTI futures contract on 19 May also led to a significantly lower number of contracts being traded. The volume of trade for the June contract was just 1,790 in early Asian trading compared with 32,755 for the July contract.
The rebound comes after WTI May turned negative last month. The US crude benchmark price went negative for the first time, settling at -$37.63/bl on 20 April the day before it expired. But the US Commodity Futures Trading Commission has warned of a potential return of negative prices in contracts for oil and other commodities because of unprecedented conditions created by Covid-19.
Prices have increased amid tighter supplies. US oil services firm Baker Hughes said that the country's drilling rig count fell by 35 to 339 last week, adding to a record low as crude prices remain too depressed for most operators to maintain stable drilling plans.