Uncertainty about who is responsible for cleaning up mature North Sea oil fields is threatening their future exploitation, the oil industry warned the government yesterday.

Uncertainty about who is responsible for cleaning up mature North Sea oil fields is threatening their future exploitation, the oil industry warned the government yesterday.

There have been a number of amendments to the Energy Bill progressing through Parliament seeking to clarify who is responsible for decommissioning old fields as the government seeks to protect the taxpayer from liability.

But oil companies, particularly the larger ones, fear there are still grey areas that make it more risky and expensive for them to sell on mature assets to smaller companies.

Shell's George McClung said: "A lot of nice words have been said but (the government) have not really stepped up to the plate and shared risk, and that is disappointing."

He said yesterday: "The Energy Bill is looking like a lost opportunity to us and asset trades will decline."

A Business, Enterprise and Regulatory Reform spokesman said: "The government has listened to industry concerns and has amended the Energy Bill to exclude companies which have never been entitled to derive a benefit from an installation from being served with a decommissioning obligation."

Much of the industry wants guarantees companies that are merely licensees of a field, but have no economic interest in it, are left with no liability for decommissioning.