Britain's FTSE takes a hit from weaker energy stocks and Greece

* Blue-chip FTSE 100 index closes down 0.9 percent

* Royal Mail (LSE: RMG.L - news) rebounds on property sale report

* Energy shares down on weaker oil price

* Greek debt jitters hurting market sentiment (Updates with closing prices)

By Liisa Tuhkanen

LONDON, June 12 (Reuters) - Britain's top equity index fell on Friday as lower oil prices hit energy stocks and concerns over Greece's talks with international creditors weighed on sentiment.

The blue-chip FTSE 100 closed 0.9 percent down at 6,784.92 points, slightly outperforming major euro zone indexes.

The biggest weight on the index was Royal Dutch Shell (Xetra: R6C1.DE - news) , which fell 2.1 percent, trimming nearly 10 points off the FTSE 100.

Rival oil major BP dropped 2.1 percent and the energy sub-index was down 2.1 percent on cheaper oil.

Oil prices slipped after the world's top crude exporter Saudi Arabia said it was ready to raise output further if needed, potentially adding to oversupply.

Royal Mail added 2.8 percent, with traders attributing the gains to a report indicating Ballymore has emerged as frontrunner to buy its Nine Elms site in London.

The postal service fell 4.5 percent in the previous session after the British government announced it would sell half of its remaining stake.

"I don't expect that we're going to see anywhere near the momentum we would have seen when it was privatised initially, but certainly it does seem fairly valued around the 500 pence mark," said London Capital Group analyst Brenda Kelly.

Investors were also focused on Greece's stalled debt talks after the International Monetary Fund ramped up the stakes on Thursday by announcing its delegation had left the negotiations in Brussels because of differences with Athens.

"Whilst investors have had plenty of time to reduce their direct exposure to Greece, any exit of the country from the euro zone will generate questions over the resolve and future of the European Union," Hargreaves Lansdown (LSE: HL.L - news) equity analyst Keith Bowman said.

A government official said on Friday that Greece is ready to submit counter-proposals to bridge differences with its creditors and will restart negotiations in Brussels on Saturday.

Athens needs a deal to unlock aid before the end of the month when it is otherwise set to default on a 1.6 billion euro ($1.8 billion) repayment to the IMF. That could trigger capital controls and possibly push Greece out of the euro zone.

Among mid caps, Bwin.Party fell 7 percent after saying two of its shareholders had decided to place up to 50 million shares in the online gambling firm.

Petra Diamonds (LSE: PDL.L - news) dropped 6.9 percent after forecasting full-year revenue below market expectations.

The miner, which has four producing mines in South Africa and one in Tanzania, had warned in April that full-year results would be below market consensus due to variability in grade and production mix. (Additional reporting by Atul Prakash; Editing by Susan Fenton/Ruth Pitchford)