FTSE retreats from 10-wk high, Petrofac slumps after warning

* Blue-chip FTSE 100 index falls 0.3 percent

* Petrofac (Frankfurt: A0HF9Y - news) plummets 16.7 pct after profit warning

* FTSE 100 less than 2 pct away from record high

By Atul Prakash

LONDON, May 9 (Reuters) - Britain's top share index slipped from a 10-week high on Friday, with energy services group Petrofac slumping after a profit warning and aero-engines maker Rolls-Royce hurt by broker downgrades.

Tensions in Ukraine also prompted investors to take some money off the table after recent gains, analysts said.

Petrofac fell 16.7 percent after warning its 2014 net profit would fall by as much as 11 percent to between $580 million and $600 million due to a poor performance from its Integrated Energy Services division.

"The profit warning from Petrofac provides a reminder as to the potential punishment in missing market expectations. Worries over Russia and Ukraine also persist," Keith Bowman, equity analyst at Hargreaves Lansdown (LSE: HL.L - news) , said.

Tensions in Ukraine have been prompting investors to stay cautious. The situation remained fragile with pro-Moscow separatists in the east of the country ignoring a call by Russian President Vladimir Putin to postpone a referendum on self-rule, declaring they would go ahead on Sunday with a vote that could lead to war.

Rolls-Royce fell 1.2 percent, pressured by a downgrade by Barclays (LSE: BARC.L - news) to "underweight" from "overweight" and a cut in its target price for the stock to 930 pence from 1,225p. The downgrade followed a reduction in its target price by JPMorgan to 1,300p from 1,350p on Thursday.

"Slow growth over the next two years, high exposure to a single yet-to-enter service aircraft, significant cash and margin headwinds, accounting concerns, and questions over capital allocation lead us to our 'underweight' rating," Barclays said in a note.

Petrofac and Rolls-Royce were among the biggest decliners in the blue-chip FTSE 100 index, which fell 0.3 percent to 6,820.21 points by 0823 GMT after rising to a high of 6,840.37 on Thursday, its highest since late February.

The index was just short of 2 percent away from its record high set in December 1999 and charts suggested it had the potential to set new highs in the near future.

"From a longer-term perspective, the FTSE 100 index is reaching a 15-year resistance from the 1999 and 2007 peaks," Dominic Hawker, technical analyst at Messels, said.

However, a "breadth indicator" that measures the percentage of stocks trading above their 200-day average was not overbought and suggested the FTSE 100 could still gain upward momentum, Hawker said. "I still remain positive that the market can break out" (Editing by David Holmes)