* Plan for formal trading joint venture dropped after sanctions
* Saras Q1 comparable core earnings rise to 144 mln euros
* Misses analysts' forecast of 155 mln euros (Adds detail, context)
MILAN, May 14 (Reuters) - Italian oil refiner Saras will open a trading business in Geneva in the coming months to boost ties with its Russian investor Rosneft, Chairman Gian Marco Moratti said after reporting a jump in first-quarter core profit.
The two companies abandoned plans for a trading joint venture last month because of western sanctions over Russia's involvement in the Ukraine crisis, but Saras expects its unilateral move to aid cooperation.
"We announce the decision to start a trading company in Geneva in the coming months, also with the purpose of developing further the cooperation with Rosneft," Moratti said in a statement without providing further details.
At the time the joint venture plan was shelved, Saras Managing Director Dario Scaffardi said the company will exchange trading information with Rosneft but without a formal company structure, adding that the new Saras business would be located near Rosneft's trading offices.
Rosneft bought a 21 percent stake in Saras two years ago and the head of the Russian group, Igor Sechin, has said he would be interested in raising its stake.
Saras said on Thursday that improved market conditions and a rebound in refining margins pushed comparable core earnings to 144.2 million euros ($165 million) in the first quarter, up from 8.4 million euros in the same period last year.
Though the figure was up sharply year on year, analysts had expected core earnings of 155 million euros, according to a consensus forecast provided by the company. ($1 = 0.8753 euros) (Reporting by Danilo Masoni; Editing by David Goodman)