New Delhi, Oct 31 - India and the US, the world's largest democracies, need to work together to win the battle against extremists in Afghanistan, former US president George W. Bush said here Saturday.

Addressing the Hindustan Times Leadership Summit here, Bush also paid handsome tributes to Indian democracy and Prime Minister Mamohan Singh, calling him a "really good man".

"The US and India should work together to win the war in Afghanistan," Bush said in a brief speech made before a select audience.

"If the Taliban, Al Qaeda and extremists are allowed to take over Afghanistan, they would have a safe haven again," he warned.

Bush called India "a modern and vibrant nation" and said the US and India were united by common interests.

"I really, really like your prime minister. I am proud to call him a friend," he said, adding that Manmohan Singh was "really a good man".

He said he had great respect for India and said the two countries enjoyed a "special kinship".

"India is a modern and vibrant nation," the former president said. He added that India was "a tolerant, peaceful and multi-religious democracy" with a "dynamic middle class" and "a force for stability in one of the world's most strategic places".

Bush referred to the India-US nuclear deal signed during his presidency and said Washington "recognises India's nuclear weapons programme".

He said India was helping the world to recover from the world's financial crisis.

Bush paid his "deepest condolences" to the victims and the families who suffered in the Mumbai terror attack of November 2008 that left some 170 people dead.

He also referred to the terrorist assaults on the Indian parliament and on the Indian embassy in Kabul.

"Both our nations are engaged in an ideological struggle," he said. The two countries sought "to advance our values of liberty, tolerance and hope".

He said the US and India should have one of the best relationships in the world. "It is not going to happen immediately." (IANS)