The difference in price between the European and US benchmarks for crude oil has widened to its highest level in more than a year, suggesting there will be windfalls for hedge funds and traders that have been betting the two commodities would revert to their historical relationship.

The US benchmark, West Texas Intermediate's premium over the European benchmark, brent crude, has widened to reach $3.60 today. Brent crude was trading at $83.90 and West Texas Intermediate was trading at $87.50 this morning, both at record highs.