London - Britain's top equity index lost ground on Friday as weaker mining stocks weighed on the market, although supermarket group Tesco rose after its sales fell less than forecast.

Tesco's shares advanced 3.6 percent after its first quarter performance suggested a tentative recovery in its key home market could be starting to move onto a stronger footing.

Tesco was the best-performing stock in percentage terms on the blue-chip FTSE 100 index, which was down 0.7 percent at 6,761.25 points, with global equity markets pegged back by persistent concerns over Greece's debt problems.

Without a deal at the weekend to unlock frozen aid, Greece, which has received two bailouts worth 240 billion euros ($268.85 billion) since 2010, is set to default on a repayment to the International Monetary Fund due on June 30.

“The market is coming under pressure, but there is still a chance they will reach a last minute agreement on Greece, as they have done in the past,” said Dafydd Davies, partner at Charles Hanover Investments.

Mining stocks took the most points off the FTSE, with the FTSE 350 Mining Index down 1.4 percent. Miners count for about a tenth of the overall FTSE 100.

Traders attributed the drop in mining stocks to a note from research firm Morningstar which forecast steel demand in China - the world's biggest metals consumer - had peaked.

A slump in the Chinese stock market on Friday also put more pressure on the sector, which is particularly sensitive to the state of the Chinese economy.

The FTSE 100 hit a record high of 7,122.74 points in April but has since retreated and is now some 5 percent below that record high. The index remains up around 3 percent since the start of 2015, less than a 14 percent gain on the broader, pan-European FTSEurofirst 300 index.