Fr Patrick Welch, a leading figure in the US-based organisation Rescue America, said the group's followers might blockade clinics and use heavy chains to block doors.
Its national director, Don Treshman, who is on bail with a warning not to involve himself in actions leading to violence or public disorder, said: 'We are getting more involved with the British pro-life movement. We are planning a mass offensive here.'
Fr Welch, a Washington priest based in Puerto Rico, is the latest member of the organisation to arrive in Britain. He was detained at Heathrow airport by immigration officials and said he was questioned about militancy before being allowed into the country. He said: 'We shall be involved in various acts of direct action here to save babies' lives. Violence I do not mean. I mean direct action. The violence is inside the clinics.'
Fr Welch said members of their new organisation Rescue Britain would go to clinics peacefully and with a non-violent attitude.
He and Mr Treshman accused the International Planned Parenthood Federation, which has its headquarters in London, of racism. They claim that the planned parenthood policy is aimed at controlling numbers in the Third World, an allegation denied by the federation.
A spokeswoman for the International Planned Parenthood Federation, Frances Perrow, said:'We address the abortion issue by providing family planning to reduce the number of unwanted pregnancies. If they (Rescue America) respect women and wish to reduce the number of abortions they should work with us on this approach.'Reuse content