UPDATE 1-Britain may order 14 F-35 jets as early as next week-sources

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By Brenda Goh and Andrea Shalal-Esa

LONDON, Jan 23 (Reuters) - Britain may announce an order for 14 Lockheed Martin-built LMT.N F-35 super-stealth jets as early as next week, three sources familiar with the talks told Reuters.

The so called 'Main Gate 4' order, for the F-35 B vertical take-off variant of the Joint Strike Fighter, would mark the Britain's first firm F-35 purchase since it committed to buying 48 planes in 2012.

It has so far taken delivery of three training jets.

Britain's Conservative-led government was embarrassed by its decision two years ago to flip-flop on which variant of the radar-evading aircraft to buy, which cost the British taxpayer at least 74 million pounds ($122.72 million).

The sources, who requested their names were not used because they were not authorized to speak publicly, said the order was for 14 aircraft and that the announcement could come before the end of January ahead of a visit by Britain's defence secretary, Philip Hammond, to Washington on Feb. 4-6.

Another source close to the Ministry of Defence said a decision was due in the next few weeks. The Ministry of Defence and Lockheed Martin declined to comment.

The F-35, considered to be the world's most expensive weapons program at $396 billion so far, was designed to be the next-generation fighter jet for the U.S. Air Force, Navy and Marines and has been likened to a flying computer with sensors that can detect enemy threats 200 miles away.

It is being built by the United States, Britain and seven other co-development partners - Italy, Turkey, Canada, Australia, Denmark, Norway and the Netherlands.

British companies such as BAE Systems BAES.L and Rolls Royce build 15 percent of each F-35 aircraft. The project is projected to create and support more than 24,000 jobs across the country.

On Thursday, Lockheed's Chief Financial Officer Bruce Tanner told reporters the company expected foreign orders to increase further in 2014, with international sales expected to account for just under 20 percent of the company's overall sales in 2014.

He said the F-35 accounted for 16 percent of Lockheed's revenues in 2013, and that number would grow again this year. ($1 = 0.6030 British pounds)

(Additional reporting by Andrew Osborn; editing by Guy Faulconbridge)

((brenda.goh@thomsonreuters.com)(+44 020 7542 2230)(Reuters Messaging: brenda.goh.thomsonreuters.com@reuters.net))

Keywords: BRITAIN FIGHTER