Oil prices were lower in quiet early trade following Friday's pre-weekend rally amid ongoing terrorist scares in London. At 10.54 am, September-dated Brent futures contracts were down 40 cents at 57.18 usd a barrel. Meanwhile, US benchmark September-dated contracts were down 33 cents at 58.36. "Trade is very quiet, with some buying in the dips," said Informa Global Markets analyst Peter Luxton. Prices dipped slightly as this year's seventh tropical storm, Gert, continued to weaken and is expected to dissipate over the mountains of central Mexico later today, US forecasters said. Separately, Statoil ASA stopped production at two North Sea oil fields, Huldra and Veslefrikk after finding a cracked lifeboat. Statoil said the production halt reduces daily oil output by 30,000 barrels of oil and roughly 6 mln cubic metres of gas. The fields were shut on Saturday, and will not resume production until the maintenance programme has been completed later this week. Informa's Luxton said: "The damage is not due to the actual oil infrastructure and is a temporary problem," which the market will not be worried by. The latest weekly Commitment of Traders Report -- an account of the previous week's trading from the US commodity regulator -- reported heavy selling of oil stocks last week. The losses were explained by the stronger than expected gains in US stockpiles in the weekly inventory report. The losses in US inventories were not as bad as participants had expected after hurricane Emily last week.