CONOCO has agreed to

purchase interests in three North Sea natural gas fields from Canadian Occidental Petroleum for $C210m (#82m).

US-based Conoco has increased its interest in the

Vulcan and South Valiant fields to 50% from 42.1% and 37.5% respectively.

It is already the operator of both fields.

Conoco has also taken a 30% stake in the Caister field and a 15% interest in the Caister Murdoch System gas pipeline, increasing its stake in the pipeline to 42.25%.

Conoco's UK natural gas reserves will be boosted by 83 billion cubic feet and its daily production will increase by about 35 million cubic feet.

The agreement also includes the purchase of a number of long-term gas supply contracts and Canadian Oxy's interests in four discoveries and three

exploration blocks.

Calgary-based Canadian Oxy said the $C210m (#82m) sale of its UK offshore assets to Conoco formed part of a wider deal to dispose of $C370m (#144m) of non-core assets.

It has also sold a series of properties in British Columbia and Alberta and plans further disposals.