NEW DELHI: India's main opposition leader, Hindu hardliner Narendra Modi, on Sunday vowed a corruption-free government and a tough stand against rival Pakistan if his party wins elections next year.

Modi described Prime Minister Manmohan Singh as weak and his government as riddled with corruption, as tens of thousands of supporters screamed the opposition leader's name at a rally in a park just outside New Delhi.

“The coalition (government) is now addicted to corruption and instead of finding solutions to end the culture of graft, it stops functioning,” Modi told the crowd, many waving party flags and wearing Modi face masks.

“India needs a dream team and not a dirty team in 2014 and people must decide that during the elections,” he declared in a speech lasting just over an hour.

The rally was Modi's first in the capital since he was elected the opposition Bharatiya Janata Party's (BJP's) prime ministerial candidate for national elections next year.

The rally helped launched the BJP's campaign for the Delhi assembly elections, to be held later this year and seen as a dry run for the national polls.

The BJP is seeking to overthrow the Congress-led coalition government, which has been embroiled in a string of graft scandals and is desperate to boost sluggish growth, after almost a decade in power.

Modi branded premier Singh as too weak to raise the issue of attacks on Indian soil, which India blames on Pakistani-based militants, during his first talks with his Pakistani counterpart later on Sunday.

Singh will sit down on the sidelines of the United Nations (UN) General Assembly with Prime Minister Nawaz Sharif, who has called for improved ties between the nuclear-armed neighbours since he was elected in May.

“Today the prime minister meets Nawaz Sharif but the country doubts whether the prime minister has the courage to discuss the issue of terrorism unleashed on us by Pakistan,” Modi said.

Modi, the chief minister of the western state of Gujarat, is a polarising figure, tainted by deadly anti-Muslim riots on his watch in 2002, but also credited with turning Gujarat into an economic powerhouse.

During the riots of 2002, as many as 2,000 people were killed, mainly Muslims. He is accused of turning a blind eye to the violence but denies any wrongdoing.