Prime Minister Gordon Brown vowed a renewed effort to defeat the Taliban insurgency, hailing the next months as critical while meeting troops in Afghanistan on Sunday, AFP reported.
Brown made an unannounced visit two weeks after ordering 500 extra British troops into the war alongside a surge of 30,000 American forces as part of a sweeping new US strategy to turn around the eight-year war.
He held talks with Afghan President Hamid Karzai at a military base in Kandahar, the southern province where the Taliban were born and one of the deadliest battlefields for NATO and US troops since the 2001 US-led invasion.
In an unusual move, Brown spent a foggy night on the sprawling base in a simple room with limited heating, sharing a shower bloc and latrine with troops, before heading into a breakfast meeting with British commanders.
The prime minister inspected new military hardware, including drones, that London has dispatched to Afghanistan in a bid to counter controversy over alleged short supplies, and wished British troops Christmas greetings.
"The combined effort of allied forces with the Afghan government is the way we will defeat the insurgency, the way we will stop Al-Qaeda having any space to operate in Afghanistan," he told a news conference with Karzai.
"I think the next few months are obviously critical," Brown told reporters travelling with him.
The extra deployment, which will boost the number of British forces in Afghanistan to more than 10,000, would arrive "in the next few days", he added.
Brown said equipment for the British mission, which is the second-largest behind the US contingent, was "improving every day" and said the number of helicopters had doubled in the last three years.
"These things are being done in a way that is calculated to weaken the Taliban and show they can't win this campaign," he said.
Karzai, who is under Western pressure to clamp down on corruption and has yet to unveil a government since being inaugurated after a re-election steeped in fraud, pledged do "a lot more" in building an accountable administration.
"We need to have a government that is responsive to the needs of the Afghan people. That's our responsibility and we will be taking a lot more measures," the president said.
The British leader welcomed his remarks.
"Of course, people will judge what happens by results, but I think we have seen a determination on the part of President Karzai to take new action against corruption," Brown said.
He admitted it had been "a difficult year" alluding to British troop losses in Afghanistan at 100 in 2009, making it the deadliest year for the country's armed forces since the 1982 Falkland's War, but said morale was high.
Officials said Brown's visit marked the first time a British prime minister had spent a night in a theatre of war in living memory.
From Kandahar he flew by helicopter to Helmand, low over desert plains to see Afghan soldier recruits being put through their paces by British trainers and being taught to look for bombs with state of the art bomb detectors.
British troops are based in Helmand, the heartland of opium production in Afghanistan which has become one of the deadliest battlegrounds in the country.
Brown said the Afghan army, currently 90,000 strong, will increase over the next year to around 135,000 and some Afghan districts could be handed over to local control in 2010.
Karzai promised to send 10,000 extra Afghan troops to Helmand for training, Brown said.
The United States has made training Afghan security forces the cornerstone of a bid to bring a quick end to the war and allow US troops to start withdrawing as early as July 2011.
Britain is hosting a conference in London on Afghanistan on January 28, at which Karzai is expected to be set tough new targets so foreign troops can start to hand over control to Afghan troops and police.
Brown described the Afghan border areas with Pakistan "the location of choice for Al-Qaeda" and "the epicentre of global terrorism" reiterating that three quarters of terror plots discovered in Britain have roots to the area.