* Q1 EBITDA 183 million euros, vs forecast 195 million
* Q1 net loss 20 million euros
* Margin pressure to continue until gas contracts resolved
* Confirms guidance for year EBITDA around 900 million euros
(Adds detail, background)
MILAN, May 9 (Reuters) - Edison, Italy's No. 2 power company, said pressure on margins would continue until it renegotiated long-term gas contracts, after weak gas results sent core first-quarter earnings down 43 percent.
Edison said on Monday earnings before interest taxes depreciation and amortisation (EBITDA) was 183 million euros, below a 195 million euro Thomson Reuters forecast of four analysts.
Edison is in the process of renegotiating long-term gas contracts whose prices have fallen below spot prices, weighing on margins.
Margin pressures will continue until the contracts are renegotiated or arbitration proceedings resolved, Edison said, adding it still expected full-year EBITDA of around 900 million euros.
Edison is controlled by French utility EDF and Italian regional utility A2A through a shareholder pact.
On March 15, shareholders agreed to extend the pact by six months to give them more time to reach a deal on the 4.6 billion euro company. (Reporting by Stephen Jewkes; Editing by Dan Lalor)