Anti-war campaigners opposed to Britain's use of armed drones in Afghanistan on Saturday marched on a military base that this week began hosting the aircraft's human operators for the first time.
Royal Air Force (RAF) pilots had been operating Reaper aircraft to support British troops fighting the Taliban in Afghanistan remotely from a base in Nevada in the United States.
But this week the operations were relocated to Britain for the first time, to RAF Waddington in Lincolnshire in eastern England, the Ministry of Defence said.
About 200 demonstrators marched to the base in Saturday, according to the BBC, to show their opposition to what campaigners said marked a "critical expansion in Britain's drones programme".
"Drones are indiscriminate weapons of war that have been responsible for thousands of civilian deaths," said a statement from the Stop the War Coalition.
"Rather than expanding the UK's arsenal, drones should be banned, just as landmines and cluster munitions were banned."
Prime Minister David Cameron announced in December 2010 new funding to increase the Reaper programme, although there are no plans to base or fly the drones in Britain, officials say.
A spokesman for the Ministry of Defence said people were entitled to demonstrate but insisted the military did "everything possible" to avoid civilian casualties.
"We would stress that UK Reaper aircraft are piloted by highly-trained professional military pilots who adhere strictly to the same laws of armed conflict and are bound by the same clearly-defined rules of engagement which apply to those operating traditionally-manned RAF aircraft," he said.