The US is claiming success against a resurgent Taleban

He was speaking after meeting President Hamid Karzai during a visit to the country.

Mr Rumsfeld made no commitment to increase the number of American troops, and said that ultimately security in Afghanistan was the responsibility of the Afghan people.

Afghanistan has seen a resurgence of activity by suspected Taleban fighters and their supporters in recent months.

"I certainly agree that an expansion of Isaf would be a good thing," Mr Rumsfeld said in response to a question at a joint news conference with Mr Karzai.

The US is keen to show its backing for Karzai

"For whatever reason, there have not been countries lining up to expand Isaf...

"But in the last analysis, the security in Afghanistan is the responsibility of the Afghan people.

"The presence of foreign forces is a helpful thing for a period. It is an important thing for a period but it is an anomaly; it is not a natural thing," he said.

During Mr Rumsfeld's visit, US General John Vines said the Taleban had been attempting to re-form in large groups for several months, but they had been thwarted.

He added that US and Afghan troops in the south and east of the country had killed up to 200 Taleban fighters in the past 10 days.

Rebuilding

Mr Rumsfeld struck an upbeat note on Afghanistan's overall situation.

He said that on his fourth visit in less than a year and a half he had seen progress, with increased economic activity, continuing reconstruction and improved security.

Before arriving in Kabul, Mr Rumsfeld flew to a remote US base in Gardez, south of the capital, where 80 American soldiers are stationed.

They are involved in tackling militia fighters and are also helping with reconstruction projects, such as repairing schools, opening roads and digging wells.

The Afghan capital was under tight security blanket for Mr Rumsfeld's visit, with extra roadblocks set up at key points in the city.

Hours before the defence secretary's arrival, suspected Taleban fighters fired rockets at a local administrative office in the troubled province of Paktika, along the Pakistan border.