Brent held above $108 a barrel on Monday while U.S. oil futures declined ahead of a contract expiry, widening the spread between the two benchmarks after reaching parity in the previous session for the first time since 2010.
WTI earlier on Monday extended its premium over Brent but reversed gains following the opening of trade in the United States as investors rolled into next month's contract ahead of the August contract expiry later in the day, traders said.
"The market leadership is back with WTI. We're seeing that in volumes traded and open interest that is increasing in WTI," said Olivier Jakob, analyst at Petromatrix.
Hedge funds amassed record bets on rising U.S. crude oil prices in the week to July 16, trade data by the U.S. Commodity Futures Trading Commission (CFTC) showed.
The convergence of the two front-month benchmarks comes as increased pipeline capacity has drained the glut of oil at the WTI delivery point of Cushing, Oklahoma, to the U.S. Gulf Coast, where refinery demand has been high. Stocks at Cushing have fallen to 46 million barrels from 52 million in January.
The strong backwardation between the September and October WTI contracts, when the front month price is higher than the next one, has been the main driver in the contract's recent rally, according to Jakob.
The WTI September/October spread was at around $1.80, with the August contract expiring later on Monday. Prior to Friday, it had last traded above Brent in October 2010.
"The extraordinarily strong backwardation is strengthening and bringing everyone into the WTI," Jakob said.
At the same time, the global benchmark Brent could find support from a stronger demand growth outlook and supply risks in the Middle East and Sudan, according to Carsten Fritsch, analyst at Commerzbank.
A pledge by the Group of 20 nations, which account for 90 percent of the world economy, to put growth before austerity has fuelled hopes of a recovery in the consumption of commodities.
Speculators increased net long positions in Brent crude oil futures in the week to July 16, data from the IntercontinentalExchange (ICE) showed on Monday.