Foreign ministers from 70 nations, including India's External affairs Minister S M Krishna are attending the conference seeking an end to the conflict in Afghanistan, drafting plans to hand over security responsibilities to local forces and quell the insurgency with an offer of jobs and housing to lure Taliban fighters to renounce violence.
Describing it as a "decisive time", Brown said by the middle of next year, "we have to turn the tide in the fight against the insurgency."
Afghan President Hamid Karzai said his country could need foreign support for its security forces for up to 15 years.
"With regard to sustaining them until Afghanistan is financially able to provide for our forces, the time may be extended up to 10 to 15 years," Karzai said.
He said with regard to training and equipping the Afghan security forces, "five to 10 years will be enough".
A possible offer of talks with moderate Taliban is high on the agenda of the conference jointly hosted by the United Kingdom, United Nations and the Afghan government.
The conference is expected to agree a $ 500 million five-year fund for President Karzai to "buy off" insurgents who are not ideologically committed to destroying the West.
Under the proposal, the Afghan leader will have to agree to international monitors to strengthen an anti-corruption campaign in his government.
Downing Street confirmed that Britain will make a contribution of a "few million".
Germany has agreed to $70 million over five years and the bulk of the money will come from the Japanese aid budget to Afghanistan, diplomatic sources said today.
US Secretary of State Hillary Clinton, UN Secretary-General Ban Ki-moon and North Atlantic Treaty Organisation chief Anders Fogh Rasmussen also joined talks aimed at setting targets to transfer security control of several Afghan provinces to the local police and military by the end of 2010.
Brown said the conference would set a target for Afghanistan to increase its military to 1,71,600 by October 2011, and boost police numbers to 13,400 by the same date.
The London talks aim to plot an eventual exit from Afghanistan for Western nations amid declining support for the war as military casualties surge.
India has cautioned against accepting the "superfluous distinction" between good and bad Taliban and asserted that as a regional power it would like to be a part of the solution in the restive country.
External Affairs Minister Krishna met his British counterpart David Miliband on Wednesday and told him that "India would like things to get settled" in that country.
Krishna told Miliband that the Al Qaeda's propaganda of creating a distinction between the good and bad Taliban should not confuse the issues of terror.
Krishna told his British counterpart that "the Al Qaeda and its various manifestations and incarnations in different names and in different times should not confuse the issue on terror".
"India has seen through the games of the Taliban that they were trying to create a superfluous distinction between good Taliban and a bad Taliban," he said.
Krishna said Talibanism was "terror driven" and India's assessment on the issue was "somewhat different".
On India's role in the regional council on Afghanistan, Krishna on Wednesday said: "Any development in Afghanistan will have far-reaching implications for India. Hence from that angle international engagement assumes special importance for New Delhi."
Brown had just a couple of days ago eluded to India's role in Afghanistan.
Brown, who has taken the initiative for the landmark conference, said the neighbours of Afghanistan should come together to help sustain an infant democracy like Afghanistan.
"India has a big role to play," he had said.
Krishna said India appreciated Brown's approach to Afghanistan and "as a regional power we would like to be part of the solution, not the problem".
Image: (Front row, from left) Afghanistan's President Hamid Karzai and Britain's Prime Minister Gordon Brown. (Back row, from left) US Secretary of State Hillary Clinton and Asia Development Bank Director General, Central and West Asia Department, Juan Miranda at the 'Afghanistan: The London Conference' on Thursday | Photograph: POOL New / Reuters
Pak envious of India's dominance in Afghanistan?
No problems if drones used against Taliban: IAF
India watching Pak closely: Krishna
Taliban blasts CIA's secret base, 8 killed
India wants to normalise ties with Pak: Krishna