Gordon Brown has promised fresh aid to help rebuild Afghanistan's shattered economy as British and Afghan troops seized a key strategic town from the Taliban.The Prime Minister flew into the capital, Kabul, for talks with President Hamid Karzai on Monday as the Afghan Defence Ministry was announcing that Musa Qala in Helmand province had been "completely captured" after four days of heavy fighting.Mr Brown immediately promised to follow up the victory with new reconstruction projects in the area in an attempt to secure the loyalties of the local population and ensure that the town does not fall back into the hands of the Taliban.In a joint news conference with President Karzai, he said: "What is happening in Musa Qala is very important in the fight against the Taliban."When that action is completed, we will give support for the economic and social development of the area."There is no doubt that succeeding in Musa Qala will make a huge difference both to how people see the weakness of the Taliban in the future and the ability of the government to build, not just militarily and politically, but with social and economic progress for the people of the area."Nato's International Security Assistance Force (Isaf) was more cautious than the Afghan Defence Ministry, simply confirming that international and Afghan troops had entered the outskirts of the main part of the town.It said that the pace of their advance was limited by the need to minimise the risk of civilian casualties and to ensure that their own troops were not caught by improvised explosive devices - roadside bombs - left by the Taliban.The capture of Musa Qala, in the centre of Helmand's opium poppy belt, will be seen as hugely important for the international coalition in Afghanistan, particularly the British.British troops pulled out of the town last year after striking a highly controversial peace agreement which gave responsibility for security to the Afghan elders.Four months later, in February, it was overrun by the Taliban and has since become a major hub of the heroin trade which helps finance the insurgency.The test now for the international forces and the Afghan Army, which they trained, will be whether they can continue to hold it.Taliban spokesman Qari Yousef Ahmadi said that their fighters had simply made a tactical withdrawal."Because of the massive bombings this morning, the Taliban didn't want to cause more casualties, so this afternoon all the Taliban left Musa Qala," he said.Before flying in to Kabul, Mr Brown visited British troops at Camp Bastion, their main base in Helmand, just 70 miles away from the scene of the fighting.Addressing members of 40 Commando Royal Marines, he paid tribute to the "huge bravery" they had shown in taking on the Taliban."This is one of the most challenging of environments, this is one of the most difficult of tasks, this is one of the most testing of times," he said."I know that the work you are doing today and in the next few days is important for the whole future in Afghanistan."Following his talks with President Karzai, Mr Brown - who is due to make a major Commons statement on Afghanistan on Wednesday - emphasised the importance of the reconstruction effort alongside the continuing military operations.He promised the UK would continue to deliver support for the building of schools, the development of healthcare facilities and the creation of small businesses, as part of the wider economic and social development of the country."Our support will continue over these next few years to make it possible not only for the security of the Afghan people but also the economic and social development of your country so that people can have a stake in the future," he told President Karzai.© Independent Television News Limited 2007. All rights reserved.