Disappointing oil exploration results in the Gulf of Mexico are upsetting the hopes of US oil majors for big new findings in an area free from interference by foreign, state-owned oil companies.

Wood MacKenzie, the energy consultancy, said in a new report that findings in the Gulf in 2007 were the lowest of the past decade. With a total of 553m barrels of oil equivalent, these new reserves were less than half of what was found in 2006.