It would be the first time that British paratroopers have jumped into action since the Suez conflict 50 years ago, said the weekly British newspaper.
Citing senior defence sources, the broadsheet said 600 troops from 2nd Battalion, the Parachute Regiment, were on standby to fly to Afghanistan within 12 hours and carry out an airborne landing within 24 hours.
Top British diplomats warned last week that a planned assault on opium producers was likely to result in heavy fighting, the newspaper said.
Therefore, military planners have drawn up a contingency plan in which a parachute battalion would jump from six Hercules C-130 transport aircraft to reinforce British Royal Marines in southern Afghanistan.
Britain has around 5,000 troops in the war-shattered central Asian country.
Commanders of NATO's International Security Assistance Force have said they are stretched in their fight against the resurgent militants and need more manpower and equipment to fight a stronger than expected campaign.
The violence has peaked this year: more than 3,000 people have been killed, most of them rebels said to be with the Taliban movement forced from government in late 2001 in a US-led invasion.

Copyright AFP (Agence France-Presse), 2006