|Singh, left, and Karzai, right, said they had agreed on a 'shared commitment to combating terrorism' [EPA]
India's prime minister has pledged $500m in fresh aid to Kabul in a move likely to raise Pakistani fears about Indian influence in Afghanistan in the wake of Osama bin Laden's killing.
Making his first visit to the Afghan capital in six years, Manmohan Singh met Hamid Karzai, the president, amid growing calls in the US for a quicker withdrawal of its troops from Afghanistan following the death of the al-Qaeda leader.
Any rapid reduction of US forces in Afghanistan would cause India concern as it fears the country could become dominated by a Taliban-influenced government friendly towards its arch-rival Pakistan.
"India's development assistance commitment is approximately $1.5bn, but there are still gaps," Singh told a news conference with Karzai.
"We now have a better idea of where we can do more ... We have made a fresh commitment of $500m over the next few years."
He also took a swipe at Pakistan by calling for a "thorough investigation" into bin Laden's presence in the country, adding to widespread accusations of Pakistani incompetence or even complicity.
Pakistan has rejected the charges.
Singh said priority areas for the fresh injection of aid would be social programmes, agriculture and infrastructure in the poverty-stricken country.
Singh also said India strongly supported a plan by Kabul to reconcile with Taliban fighters, New Delhi's first public backing of the plan.
India was rattled when the US and NATO agreed earlier this year to a plan by Karzai to reintegrate Taliban fighters and reconcile with their leaders after nearly 10 years of fighting.
Successfully balancing the competing interests of India and Pakistan, who have been jockeying for influence in Afghanistan for years, has been a challenge for the US.
Washington recognises that fighting alone will not end the war and has cautiously backed a political settlement as long as conditions are met.
One of the main conditions is that fighters renounce al-Qaeda.
The Taliban, who once sheltered bin Laden inside Afghanistan, have rejected any peace talks with the Afghan government until all foreign troops have left the country.
Singh's trip comes just over a week after bin Laden was killed by US special forces in Pakistan.
Analysts say the Taliban have been trying to distance themselves from al-Qaeda over the past few years, and have never professed any ambitions outside Afghanistan.
"We wish to see a peaceful, stable, democratic, pluralistic Afghanistan. We strongly support Afghan people's quest at peace and reconciliation," Singh told Karzai at his palace in Kabul.
"India supports firmly the unity, integrity and prosperity of Afghanistan."
In a joint statement, Singh and Karzai said they had agreed on a "shared commitment to combating terrorism that threatens both countries as well as the region".
Nuclear-armed rivals India and Pakistan, which have gone to war three times since 1947, have for decades sought to secure leverage in Afghanistan.
India is Afghanistan's biggest regional aid donor and sixth largest overall.
Pakistan derides those attempts to secure influence in what it considers its neighbourhood.
Islamabad has been concerned by governments in Kabul that it sees as too cosy with New Delhi.
India has blamed Pakistan's spy agency, the ISI, for attacks on Indians in Afghanistan aimed at undermining New Delhi's influence.
India's embassy in Kabul was hit by two bomb attacks in 2008 and 2009, killing 75 people and wounding hundreds. The Taliban claimed responsibility.
For its part, Pakistan accuses India of backing separatists in Baluchistan, an area which spills into Afghanistan. India denies the charge.
"We would like to develop friendly relations with all countries of this region, and that includes Afghanistan, that includes Pakistan as well," Singh said.