British Prime Minister Tony Blair says Afghanistan remains a key battleground in the global war against terrorism. During his first trip to the war-torn country in nearly five years, Mr. Blair said Britain would stay "as long as it takes" for Afghanistan to rebuild.

The prime minister's visit comes as Afghanistan faces its bloodiest year since 2001, when a U.S.-led coalition ousted the Islamist Taleban regime.

Monday morning, Mr. Blair met with several hundred British troops based deep inside the Taleban's traditional stronghold in Southern Afghanistan.

The British leader said the servicemen and servicewomen are fighting to help improve security not just in Afghanistan, but throughout the world.

"Here in this extraordinary piece of desert is where the future of world security in the early 21st Century is going to be played out?You're the people that are doing the difficult work. And, you should know not just you're appreciated, but the importance of the work you do is appreciated as well."

The United Kingdom has around 6,000 troops in Afghanistan, part of a 30,000-strong NATO force.

In the last year, Taleban insurgents have apparently gained ground in many parts of the country, and more than three thousand people - including 38 British soldiers - have been killed in the last 12 months.

The violence has sharply increased the pressure on NATO forces to improve security. The fighting has also weakened public support for Afghan President Hamid Karzai.

Mr. Blair met the Afghan leader Monday afternoon inside the heavily guarded capital, Kabul.

During a joint press conference afterwards, Mr. Blair vowed Britain would stay for "as long as it takes" to help rebuild the country.

"The alternative is that we go back to an Afghanistan that wasn't just misery for its people here, but end up with violence and death being exported around the world, and that's not an alternative any of us should contemplate," he said.

Both Mr. Blair and Mr. Karzai insisted there are signs of progress in Afghanistan. Mr. Karzai in particular highlighted the country's economic growth and said both health care and education facilities are being expanded and improved.

However, he conceded that drug abuse and opium production remain major problems.

According to a recent United Nations survey, the country now produces roughly 90 percent of the world's illegal opium and heroin.

On Sunday, Mr. Blair was in Pakistan for a meeting with President Pervez Musharraf. The two leaders agreed to strengthen ties and increase cooperation on regional security issues and the war against terrorism.