KABUL - BRITAIN'S Prime Minister Gordon Brown on Saturday paid a surprise visit to Afghanistan, where he spoke to troops battling the Taliban and held talks with President Hamid Karzai.

The visit came as government and military sources speaking on condition of anonymity said around 300 British soldiers had been deployed from Cyprus as part of an increase in troop levels ahead of next year's presidential election.

Mr Brown condemned Friday's 'terrible' killing of British soldiers in Afghanistan, and said that other nations must also send more troops in support of the plan.

He said the world could not rely only on the two biggest contributors, Britain and the United States, whose president-elect Barack Obama has said he will send more troops to Afghanistan.

Britain's military is feeling the pinch as it fights on two major fronts - in Afghanistan, where it has more than 8,000 troops as part of the Nato-led International Security Assistance Force (ISAF), and Iraq.

'In future, there must be proper burden sharing and that's something which we will insist upon,' he said at a Kabul press conference with Mr Karzai.

'As we look forward with president Obama's plans now about to come forward, then burden sharing is very much a part of that.' Mr Brown said he was in Afghanistan to 'take stock' of the situation.

He announced US$10 million (S$15 million) in funding to encourage registration in the election and said a taskforce of British officials had been offered to Afghanistan to root out corruption.

He also called on Pakistan and Afghanistan to work together to ensure cross-border stability in the mountainous area seen as a militants' hideout between the two nations.

'Joint action between Pakistan and Afghanistan... is essential if we're going to have peace and stability,' he said.

Mr Brown started his visit to Afghanistan in Camp Bastion, the huge British military base in southern Helmand province, where he spoke out against two fatal incidents on Friday.

'It is a terrible commentary on the Taliban that they should use a 13-year-old child as a suicide bomber,' he said, referring to one attack which killed three and involved a teenager with a bomb hidden in a wheelbarrow.

'There is disgust and horror at these tactics being used by the Taliban,' he added.

He later took a helicopter to the Roshan observation post near Musa Qala, near where the troops died and a stone's throw from where Taliban fighting has been taking place, and met Gurkha soldiers serving there.

Officials said the trip took him right up to the front line, with one claiming he got closer to fighting than any British premier since World War II leader Winston Churchill.

Mr Brown also met acting district governor Said Agha and the local chief of police before returning to Camp Bastion for a meeting with Helmand governor Gulab Mangal covering next year's elections, counter-narcotics and security.

A government source said Britain was set to confirm Monday that the troop reinforcements ahead of the elections had been carried out in the last few weeks.

A military source added they would be trying to secure prime agricultural and poppy-growing land in Helmand alongside other nations including Denmark and Estonia.

A total of 132 British personnel have died in Afghanistan since the start of operations in 2001, including the latest attacks.

International forces are fighting Taliban militia who were in power between 1996 and 2001 before being ousted in a US-led invasion after the September 11, 2001 attacks on the US blamed on Al-Qaeda operatives based in Afghanistan.

The Taliban is waging an insurgency which has gained pace in recent years. -- AFP