* STOXX 600 ends flat
* Oil majors drop after OPEC deal
* Petrofac down 30 on probe woes
* Zodiac, Safran reach deal (Adds details, closing prices)
By Danilo Masoni and Kit Rees
MILAN, May 25 (Reuters) - European shares struggled for direction on Thursday with investors hunting for fresh catalysts as a blistering earnings season that helped stocks surge to new highs nears its end.
An OPEC meeting in Vienna that disappointed some investors failed to move broader indexes but sent oil prices lower, making the energy sector the biggest sectoral faller in the region.
The Organization of the Petroleum Exporting Countries decided to extend cuts in oil output by nine months to March 2018 in a bid to drain a global glut that has depressed markets.
But some were hoping for more and that sent oil prices falling 4 percent, hitting energy stocks with Oil majors BP , Total and Eni fell between 0.9 and 1.9 percent.
In the same sector, Petrofac fell 30 percent after the British oilfield services firm suspended its chief operating officer in response to a British investigation into alleged bribery, corruption and money laundering.
The pan-European STOXX index fell 0.06 percent, staying close to 21-month highs, while Germany's DAX fell 0.17 percent after hitting an all-time high earlier in May.
After the recent run that saw record inflows into the region, some investors have turned cautious on prospects for more gains. Milan-based fund manager Anthilia Capital in Milan downgraded its exposure to euro zone stocks even though the European economy remained strong thanks to global demand.
First-quarter results have been surprisingly strong. More than four out of five companies in Europe have already reported with 65 percent of them beating earning expectations.
Some more companies reported results on Thursday with Britain's Intermediate Capital Group jumping 14 percent after its full-year results, and GVC Holdings also rose 2 percent after a first-quarter update.
British media group Daily Mail and General Trust dropped 6.8 after it warned that revenue in its information business would be lower than previously forecast.
James Butterfill, head of research and investment strategy at ETF Securities, said that now the earnings season is over the next focus points included the U.S. Federal Reserve, the ECB meeting next month and UK's general election.
French aerospace supplier Zodiac gained 0.3 percent after accepting a reduced offer from aero engine maker Safran, following a series of profit warnings. Safran's shares rose 3 percent.
Analysts at Barclays said the offer was better than expected, but they had doubts about the strategic rationale of the deal. "Having high conviction in forecasts is a challenge given Zodiac's enduring volatility," they said in a note. (Reporting by Danilo Masoni; Editing by Andrew Heavens)