With presidential elections to be held in Afghanistan next month, Miliband called on any incoming government to weed-out Afghans who he said were fighting for money as they they had no jobs or were being coerced into battle.
"We need to help the Afghan government exploit the opportunity ... and turn those who can be reconciled to live within the Afghan constitution," he said.
The foreign minister said conservative Pashtun nationalists, who wanted local Islamic rule, needed to be separated "from those committed to violent jihad globally" and given "a sufficient role in local politics that they leave the path of confrontation with their government".
Speaking about Miliband's call for talks, Paddy Ashdown, a British politician, ex-soldier and former High Representative for Bosnia and Herzegovina, told Al Jazeera: "It's puzzling, it's entirely right, it's entirely sensible - but it's not new.
"[Talks have] already been going on for a considerable amount of time.
"It's been going on openly and publicly in Saudi Arabia, where the Afghan government has been meeting the Taliban.
"It was going on more secretly two or three years ago when President Karzai [the Afghan leader] - although he knew perfectly well it was going on - objected to it, no doubt for political reasons.
"The lesson [Britain] learnt from the IRA in Belfast was that, until you have them militarily on the back foot, why should they seriously come to a negotiating table when they think they could win more on the battlefied?"
In a co-ordinated message from London, a spokeswoman for Britain's defence ministry said the "first phase" of the UK's operation "Panther's Claw" offensive in the southern Afghan province of Helmand had ended.
"There are three phases. The first was the most heavily military phase," she said.
|Ashdown said the first part of 'Panther's Claw' was the 'easy bit' [GALLO/GETTY]
"The second is a holding phase, about holding the ground, and the third is a building phase."
Ashdown said: "The question is whether we can do the next two bits, which is holding it [the captured ground] and rebuilding governance, the rule of law, reconnecting water supplies and electricity.
"In a sense, and I don't want to diminish the sacrifice by those who died, this is the easy bit.
"The difficult job is can we hold the ground or will the Taliban come back."
It was also announced on Monday that two more British soldiers had died in attacks in Afghanistan, taking the total since the operation was launched to 22 soldiers.
One soldier was killed when a vehicle taking part in "Panther's Claw" was hit by a blast, the defence ministry said in a statement.
A second soldier was killed while on footpatrol in the Sangin district of Helmand, it said.
While the focus of Miliband's message in Brussels was the role the Afghans should play in the future, he also insisted that Nato allies must engage in "burden-sharing" and send more troops and equipment and lift conditions placed on the way forces can operate.
The minister also sent a message to Pakistan, noting that any deal with former Taliban fighters on either sides of the border should only involve former fighters who are "prepared to shut out Al-Qaeda and not use violence against troops or citizens in Afghanistan".