A second operation by British Royal Marines in Afghanistan has been launched to "capture or destroy" remaining members of the al Qaeda network.

Operation Snipe began four days ago and will involve 1000 troops of the 1700 in Kabul, including members from 45 Commando, Royal Artillery and Afghan soldiers. American air and special operations forces will support the effort.

Brigadier Roger Lane confirmed that the action had begun, which will "remove the cancer of the al Qaeda network from the very heart of Afghanistan."

A Ministry of Defence spokesman said that troops had not yet encountered enemy forces.

Shadow defence secretary, Bernard Jenkin, told ePolitix.com: "This is a hazardous but necessary operation to help rid Afghanistan of the remnants of al Qaeda. Al Qaeda needs to be stabilised to assist the process to democracy."

"We wish the Royal Marines well and have every confidence in their professionalism."

The announcement follows a warning earlier this week by US defence secretary Donald Rumsfeld, that a threat from the al Qaeda network remained for the interim administration in Afghanistan.

He said at the Pentagon: "They do have it in mind that they would like to return. And they do have it in mind that they'd like to destabilise, and if possible defeat the interim Afghan authority."