The giant legs that will support the platforms used for production from the bumper Clair Ridge field have been secured in position on the seabed west of Shetland by BP.

The oil and gas company said the installation of the two jackets 50 miles off the islands was a major milestone in the £4.5 billion project to develop Clair Ridge.

Trevor Garlick, regional president for BP's North Sea business said: "The safe installation of the two jackets in to the sea bed is a fantastic achievement by the project team, and is a very visible sign of our commitment to maintaining a successful long term business in the UK."

Made of tubular steel in Norway, the jackets have been piled into the seabed in an area where the water is around 450ft deep.

They will be used to support platforms housing production and accommodation facilities and related utilities. BP expects these "topsides" facilities will be installed in 2015, with first oil to follow late in 2016.

The oil and gas major expects production to reach up to 120,000 barrels oil equivalent daily and to continue to 2050.

BP expects more than £1.5bn of the total budget under headings like drilling and engineering work to be spent in the UK.

BP is developing Clair Ridge with ConocoPhillips, Chevron and Shell.