NEW DELHI: India's Prime Minister Manmohan Singh said Friday “it would be disastrous for the country to have Narendra Modi as prime minister”.

Singh's strong attack on the Hindu nationalist ring-winger from western Gujarat state came during his first full press conference in three years.

Polls show Congress is extremely unlikely to emerge as the winner in the world's biggest election due this year, with the opposition Bharatiya Janata Party making gains under hardline leader Modi.

Singh said he will step down after elections due by May this year even if his Congress party defies predictions and sweeps to power for a third consecutive term.

“In a few months' time after the general elections, I will hand over the baton to a new prime minister,” he said in opening remarks at the press conference.

Singh, 81, had already hinted strongly at his intention to make way for leader-in-waiting Rahul Gandhi, the scion of the Gandhi dynasty which has dominated India's politics since independence.

He said Congress would announce its prime ministerial candidate in due course.

“Rahul Gandhi has outstanding credentials. I hope our party will take that decision at an appropriate time,” he added.

During his time as prime minister, Singh has seen his formerly stellar reputation built up through his work as a reforming finance minister in the 1990s tarnished by a string of corruption scandals and slowing economic growth.

He mounted a defence of his legacy, regretting high inflation, the graft scandals and weak growth in manufacturing output, but hailing his government's work for the rural poor and farmers.