A key summit on the future of Afghanistan is set to start in London with a possible offer of talks to moderate Taliban high on the agenda.Foreign ministers from some seventy countries will gather for the summit, intended to give renewed momentum to nation-building in Afghanistan.Donor countries are expected to set up a fund to help lure Taliban members back into Afghan society.But Western nations will also be asking for more details on the strategy. Afghan President Hamid Karzai has won general support for his plan to wean low-ranking fighters from the Taliban.