Rabbi Tony Bayfield, the head of the Reform movement, this week stressed that the recent statement on pluralism signed with the Liberals and Masorti was not a declaration of war on Orthodoxy.
"We don't want to go to war with anybody," he told a quarterly meeting of the Reform's lay council in London on Sunday.
But explaining last month's statement in which Reform, Liberal and Masorti leaders pledged closer co-operation, Dr Bayfield said: "We do not think that an increasingly fundamentalist-orientated United Synagogue can meet the needs of 80 per cent of the community."
He added: "We are not waging war against fundamentalism or anything like that... We need this collaboration if this community is to have the bright future it should have."