UK govt warned that investors could pull plug on green energy

* Internal government disputes cause investor concern

* Political trust needed for commitment to large projects

LONDON/PARIS, Oct 8 (Reuters) - A group of sevenmultinational companies has told the British government thatthey could halt their investment in the UK green energy sectorif state support for renewable energy wanes.

Britain is the world's biggest offshore wind market in termsof capacity and has attracted interest from global players inthe sector. But recent disputes within the coalition governmentover support for the sector has caused them concern about therisk of a political U-turn against green energy.

The seven big investors, including wind turbine producersVestas and Gamesa , told the Secretary of Statefor Energy in a letter seen by Reuters that they could taketheir money elsewhere if they feel that the risk of thegovernment turning its back on renewable energy is too great.

"Historically the UK has benefited from being known as acountry with low political risk for energy sector investments.Undermining that reputation would have damaging consequences forthe scale of future investments in the UK energy sector," thecompanies said in the letter, a copy of which was also sent toPrime Minister David Cameron and finance minister GeorgeOsborne.

The group, which also includes Alstom , Doosan, Areva , Siemens and MitsubishiPower Systems Europe, said that such investments depended on astable policy framework because large-scale energy projects takea long time to build.

Osborne on Monday gave a boost to Britain's shale gasindustry by offering hope of tax relief on such wells, a movethat environmental groups say goes against the government'spromise to be the greenest ever.

Wind turbine manufacturers GE Energy and Vestas have alreadybacktracked on setting up production facilities in Britain,showing that appetite for UK-based manufacturing was lower thanthe government expected.

Britain has one of Europe's most ambitious wind powerdevelopment targets, with a projected annual capacity growthrate of 13 percent until 2020, requiring huge investment for newplants.

(Reporting by Karolin Schaps in London and Michel Rose inParis; Editing by David Goodman)

((karolin.schaps@thomsonreuters.com)(+44)(0)(207 5426622)(Reuters Messaging:karolin.schaps.reuters.com@reuters.net))