The protest, at RAF Lakenheath, Suffolk, against a possible war with Iraq was organised by the Lakenheath Action Group, with members of Cambridge Students Against War.

A police spokesman said the three-hour protest on Monday was mainly peaceful and attended by about 60 demonstrators with 100 police officers at the scene.

He said the two women and four men were arrested for obstructing the highway and were in custody at a police station.

Lakenheath is the largest US airbase in the UK

It was not believed that any protesters had entered the base, he said.

David Higgin, from the Lakenheath Action Group, said: "A war against Iraq would result in the killing of thousands of innocent civilians.

"The evidence of imminent threat from Saddam Hussein is just not there.

"We have to do all we can to persuade Tony Blair not to join the US in an unjustified attack."

RAF Lakenheath, where the 48th Fighter Wing is stationed, is the largest US Air Force base in the UK.