Shares in Tesco were down 2 percent, reversing early gains, after Britain's biggest retailer plunged to an annual loss of 6.4 billion pounds ($9.5 billion) and failed to provide details about the planned disposal of assets such as its data-gathering arm Dunnhumby.

"Tesco's review of Dunnhumby is 'well-advanced', but there is no concrete news on its future or indeed the future of any of Tesco's other operating assets," analysts at Barclays said in a note.

The blue-chip FTSE 100 index was down 0.7 percent at 7,017.08 points by 1055 GMT. The index had been treading water since hitting a record high of 7,119.35 points last week.

Investors were monitoring a standoff between Greece's government and its creditors over reforms needed to unlock bailout funds and renewed worries that Greece might have to leave the euro zone.

"The FTSE 100 is very range-bound at the moment and lacks a clear direction," IG analyst Chris Beauchamp said.

Commercial banks knocked 11 points off the FTSE, with Standard Chartered dropping 2.3 percent after both Citi and Credit Suisse cut their target prices for the stock.

Rolls-Royce Holdings, the world's second-largest maker of aero engines, rose 3 percent after announcing that Chief Executive John Rishton would retire in July, and be succeeded by Warren East, the former leader of Britain's biggest listed technology company ARM.

Travis Perkins rose 1.6 percent after Britain's biggest supplier of building materials posted a 5.1 pct rise in first-quarter like-for-like sales.

Gambling technology company Playtech rose 2.8 percent after Goodbody Securities upgraded the stock, citing the proposed acquisition of TradeFX as a positive.

(Editing by Susan Fenton)

By Atul Prakash and Francesco Canepa