Oil rises $1 a barrel on tightening supplies

LONDON Aug 7 (Reuters) - ICE Brent crude oil futures rose $1 a barrel to $110.55 at 1136 GMT on Tuesday on supply worries stemming from North Sea maintenance, Middle East tensions and the start of hurricane season in the Gulf of Mexico, which could disrupt oil and gas production.

By 1151 GMT Brent was at $110.45 a barrel.

The Brent contract is based on four North Sea crude oils - Brent, Forties, Oseberg and Ekofisk (BFOE). An export schedule for Forties, the largest stream, is expected later on Tuesday and could show a drop in supply to a record low on the four grades combined.

In North America, investors were watching Tropical Storm Ernesto. U.S. forecasters said it should strengthen into a hurricane before hitting Mexico's tourist Yucatan peninsula. (Reporting by Julia Payne; Editing by Anthony Barker)