A serious shortage of patrol vehicles is hampering operations in Afghanistan, British commanders have told the BBC.
About 3,000 Nato troops are involved in Operation Silicon
BBC correspondent Alastair Leithead said a lack of heavily armed Land Rovers was a particular problem.
Lieutenant Colonel Charlie Mayo, spokesman in Helmand province, said only 126 of the 170 needed were in working order.
The Ministry of Defence insisted troops were properly equipped to do their job.
The complaints came just a day after UK forces took control of Afghanistan's southern provinces as part of the Nato mission there.
British soldiers are involved in Operation Silicon to drive Taleban fighters out of opium-producing areas.
Armed Land Rovers - or WMIKs (weapons-mount installation kits) - are used to protect soldiers while out on patrol or operations.
Commanders felt they had an opportunity to push the Taleban back, and with the ground still being held it's being seen as a success so far.
Mr Leithead, who is embedded with British troops, said an average of one of these vehicles a week was being lost and replacements sent from the UK often arrived late.
Lt Col Mayo said the WMIKs were taking "a hell of a hammering" in the hot and dusty conditions and said the situation was "tight, but not critical yet".
A fifth of the fleet is damaged or has been destroyed by enemy fire, he added, but more would be arriving soon.
Another vehicle, a Pinzgauer, has been fitted with extra armour to try to cover the shortfall, but there is a limit to the number of men and the amount of equipment they can carry, our correspondent said.
And the strain was increased because extra troops had recently been deployed without extra vehicles, he added.
A spokesman for the MoD denied there was a shortage and said huge investments had been made in equipment for the Army.
"The success of our forces against the Taleban shows that they are not only among the best in the world, but also among the best equipped," he said.