Oil contamination on a £20m shopping development site will cost more than £200,000 to clear and delay work by at least another two months.

The Limborough Road scheme, at Wantage, ground to a halt in July when it was discovered the land was polluted. Wantage-based consultants Bushbuy hoped to be able to start work again in October.

However, there are fears oil could seep into nearby Letcombe Brook, damaging plant and animal life.

Bushbuy commissioned a £20,000 study to assess the extent of the pollution and the steps needed to clear the site to start work.

Bill Atkinson, Bushbuy's managing director, said: "The study shows that there is quite a bit of oil that we need to take away and contain to stop it eventually running into the brook.

"We are about to put this out to contractors. Hopefully the problem will be dealt with within the next two weeks. It is annoying because we cannot carry on with the development until this is dealt with."

It is believed that the oil may have come from former occupants of the site, or an old static oil tanker that was nearby.

A revised planning application, which was expected to be decided in July, has also delayed construction work.

The finalised plan was expected to be considered by Vale of White Horse District councillors today (Monday).

The development will feature a Sainsbury's supermarket.