Britain's FTSE hovers near one-week lows as StanChart slides

* FTSE 100 down 0.2 pct at close

* StanChart (HKSE: 2888-OL.HK - news) falls after report of U.S. probe

* Wolseley (Frankfurt: A1W7PR - news) slips on cautious outlook (Recasts, adds detail, updates prices at close)

By Kit Rees and Sudip Kar-Gupta

LONDON, Sept 27 (Reuters) - Britain's top shares index hovered near one-week lows on Tuesday, weighed down by a drop in banking stocks such as Standard Chartered (HKSE: 2888.HK - news) and weaker energy company stock prices.

The blue-chip FTSE 100 index was down 0.2 percent at 6,807.67 points at its close, near its lowest level in around a week.

The FTSE gave up gains made earlier in the session following a rebound in world stock markets after Democrat Hillary Clinton, favoured by many business leaders and investors, was seen to have won the first U.S. presidential election TV debate against Republican rival Donald Trump.

The FTSE remains up by around 9 percent since the start of 2016 but it fell 1.3 percent on Monday in what was the FTSE's worst one-day percentage drop since late June, when Britain voted to quit the European Union in a shock "Brexit" vote.

Standard Charterd was the top faller, down 2.5 percent following a media report that the bank faced an investigation by the U.S. Department of Justice into whether StanChart failed to stop alleged misconduct at MAXpower Group Pte Ltd, an Indonesian power plant builder.

Standard Chartered said that it had referred the allegations to the appropriate authorities.

Royal Bank of Scotland (LSE: RBS.L - news) and Barclays (LSE: BARC.L - news) fell 1.6 percent and 1.3 percent respectively.

Shares (Berlin: DI6.BE - news) in oil major Royal Dutch Shell (LSE: 0LN9.L - news) dropped 2.2 percent, with BP also slipping 0.9 percent, hit by weaker oil prices.

The Organization of the Petroleum Exporting Countries and other oil producers, led by Russia, are meeting on the sidelines of the International Energy Forum in Algeria from Sept. 26-28, but investors are sceptical that they can agree to limit output.

"Markets are still unconvinced that an agreement will be reached with Iran downplaying yesterday the chances of OPEC and non-OPEC producers sealing a deal to curb output," said FXTM chief market strategist Hussein Sayed.

Wolseley fell 1.3 percent after the building materials distributor warned of tough market conditions as it reported results.

"The U.S. industrial market remains weak and the outlook statement mixed, citing an uncertain economic environment in some markets and continued price deflation," Jefferies analysts wrote, keeping a "hold" rating on Wolseley shares.

Travel & leisure stocks were among the top risers, with cruise operator Carnival (LSE: CCL.L - news) gaining 4.8 percent after a target price upgrade from Natixis (LSE: 0IHK.L - news) .

TUI (LSE: 0NLA.L - news) rose 1.5 percent after a TUI executive said August trading was in line with expectations and bookings from Britain did not fall as much as expected after the vote to leave the European Union. (Editing by Robin Pomeroy)