May 7 (Reuters) - Belgian chemicals group Solvay SOLB.BR reported first-quarter core earnings in line with market expectations on Thursday, supported by a favourable litigation outcome in Performance Chemicals and continued optimisation of its CO2 portfolio.

The group said its underlying earnings before interest, taxes, depreciation and amortisation were 219 million euros ($257.37 million) in the quarter, down 12.4% from last year but in line with analysts' average forecast of 220 million euros in a consensus compiled by Vara Research.

The company also said production at its peroxide site in Saudi Arabia has been halted since mid-March as a result of the Middle East conflict, adding the impact on second-quarter performance was still being assessed.

($1 = 0.8509 euros)