MUMBAI (Reuters) -S&P Global Ratings retained India's sovereign rating but raised its outlook to 'positive' from 'stable' as the country's robust economic expansion is having a constructive impact on its credit metrics, it said in a note on Wednesday.

"We expect sound economic fundamentals to underpin the growth momentum over the next two to three years," S&P said, adding that regardless of the outcome of general elections, the ratings agency expects broad continuity in economic reforms and fiscal policies.

The rating agency's positive outlook on India is predicated on its robust economic growth, pronounced improvement in the quality of government spending, and political commitment to fiscal consolidation, it said.

"We believe these factors are coalescing to benefit credit metrics," the report added.

India's marathon national election lasting six weeks, the world's largest, is in its final stage with votes scheduled to be counted on June 4, and investors are gearing up for Prime Minister Narendra Modi securing a third term in office.

(Reporting by Swati Bhat; editing by Sudipto Ganguly)