* Q4 comparable EBITDA 17.6 mln euro vs 46 mln consensus
* Share price slides over 6 percent
* Refining margin in Q4 $1.1/bl from $1.7 previous year
* Market waiting for details on Rosneft jv (Recasts lead, adds shares, analyst, Rosneft)
By Stephen Jewkes
MILAN, Feb 28 (Reuters) - Core earnings at Italian refiner Saras slumped by two thirds and missed forecasts in the fourth quarter, hit by flagging refining margins and a fallaway in demand from traditional markets.
Increasing competition has weighed on European refiners as the United States, once an attractive export market, has become a net exporter of oil products due to its shale oil boom.
Faced with competition by more efficient plants in Asia and the Middle East and crippled by high oil prices and weak fuel consumption in peripheral Europe, some of Europe's refineries are facing the threat of closure or reduced production.
Oil major Eni, Italy's biggest refiner, shut down its refinery in Sicily last year for maintenance and is due to reopen in June this year.
Saras's comparable earnings before interest, tax, depreciation and amortisation (EBITDA) in the quarter slid to 17.6 million euros ($23.1 million), well below a 46 million euro consensus provided by the company.
The refiner posted a net loss of 82.4 million euros compared with a loss of 11 million euros in the consensus.
At 1236 GMT Saras shares were the worst performer on the Italian market, down 6.2 percent at 0.868 euros.
"On refining EBITDA came in well below our expectations," Milan broker Mediobanca Securities said in a note, adding the 2013 outlook provided by the company seemed optimistic in view of warnings of high volatility in oil prices.
Saras, controlled by Italy's Moratti family, which also owns top flight soccer club Inter Milan, said this year had started with a clearly more positive trend for the refining industry with healthy demand outside Europe for both diesel and gasoline.
"The latter, in particular, showed unexpected strength," Chairman Gian Marco Moratti said.
The refiner said it expected its maintenance programme this year, lighter than that of 2012, to reduce its EBITDA by $37-46 million.
In December Saras announced an agreement with Russia's Rosneft that will allow it to tap the Russian group's crude oil portfolio in return for giving its partner access to the wider Mediterranean.
Very few details were provided at the time and the scope of the deal remains vague.
"At this afternoon's call (1400 GMT) we expect the company to provide more information on the Rosneft jv which in our view could lead to the Russian company taking an equity stake in Saras's refinery...," Mediobanca said.
Saras's Sarroch refinery in Sardinia is well positioned geographically to give Rosneft wide access to the Mediterranean area. ($1 = 0.7628 euros) (Reporting By Stephen Jewkes; Editing by David Cowell)