By Rebekah Curtis

LONDON (Reuters) - The FTSE 100 .FTSE index of leading shares ended lower on Thursday, weighed down by banks and oil stocks, with water utility Kelda Group KEL.L leading the list of losers after a broker downgrade.

On the upside, pub owner Enterprise Inns led gainers with a rise of 3.3 percent as traders cited positive sentiment from a share buyback on Wednesday, a broker upgrade and hopes of private equity bid interest in the pub sector.

The FTSE 100 index closed down 20 points, or 0.3 percent at 6,140.

But there was little economic data and many investors stayed away while U.S. and Japanese markets were closed for holidays, so trading volumes were lighter than usual.

"As this is such a thin week for economic numbers and a short week in the U.S., the markets were likely to drift," said Mike Lenhoff, chief strategist at Brewin Dolphin.

"They've had such a jolly good run that they deserve a bit of profit-taking and a breather, and that is what we are seeing."

Kelda Group fell 2.3 percent on a Citigroup downgrade and after bid speculation subsided.

Banks fell as some traders said the Bank of England's November interest rate hike had finally begun to hit markets. HBOS fell 0.9 percent and Royal Bank of Scotland lost 0.7 percent.

Oil stocks weighed as U.S. crude oil prices fell to $59 a barrel after a build-up in crude stocks in the United States. BP was down 0.6 percent and Royal Dutch Shell fell 0.5 percent.

But oil explorer Cairn bucked the trend, up 3 percent after announcing it had completed the placing of Cairn India shares on the Bombay Stock Exchange and raised 37 billion rupees ($433 million pounds).

"The least highly valued sectors in the FTSE 100 at the moment are oil stocks, miners and banks, and we would later expect a bit of catch-up in these," said Angus McCrone, senior economist at the Centre for Economics and Business Research.

ICI RISES

Chemical and paints company Imperial Chemical Industries ICI.L added 2.8 percent, having hit its highest level in nearly six years earlier in the session after a series of brokerage upgrades. It also got a boost from renewed bid speculation following the Wednesday sale of its flavours and fragrance business, Quest International.

Mobile phone company Vodafone added 1.3 percent after Swisscom said it would enter talks to repurchase its 25 percent stake in Swisscom Mobile, potentially marking the British company's exit from the partnership. It also benefited from several broker upgrades.

British tobacco shares rose after the top European Union court ruled that individuals must still pay duty on tobacco in their own countries even if they order the product from another EU state. Imperial Tobacco climbed 1.7 percent, and Gallaher Group GLH.L added 0.9 percent.

Building materials firm Wolseley dipped 0.8 percent on talk that a slowdown in the U.S. housing sector could be worse than feared, traders said. Shares in rival Hanson HNS.L were down 1.3 percent.

(Additional reporting by Alex Davidson)