They say they were told by a Muslim police community support officer that they could not preach there and that attempting to convert Muslims to Christianity was a hate crime.
The community officer is also said to have told the two men: ‘You have been warned. If you come back here and get beat up, well, you have been warned.’
A police constable who was present during the incident in the Alum Rock area of Birmingham is also alleged to have told the preachers not to return to the district.
It comes amid growing concern over the development of Islamic ‘no-go areas’.
The preachers, Americans Arthur Cunningham and Joseph Abraham, are demanding an apology and compensation from West Midlands Police.
They say their treatment breaks the Human Rights Act, which guarantees freedom of religious expression.
The preachers, who have the backing of the Christian Institute pressure group, say they will take the force to court for breaching their human rights if they don’t receive an apology.
They have accused the officer, PCSO Naeem Naguthney, of behaving in an ‘aggressive and threatening’ manner. A complaint by their lawyers said he interrupted as they spoke to Muslim youths about their beliefs.
Mr Abraham, 65, who was born a Muslim in Egypt and is a convert to Christianity, said: ‘He told us we were trying to convert Muslims to Christianity and that that was a hate crime.
‘He was very intimidating and it concerns me that somebody holding his views can become a police officer, albeit at PCSO level.’
Mr Cunningham, 48, a fellow American Baptist missionary, said: ‘He realised we were Americans and then started ranting at us about George Bush and American foreign policy.
‘He said we were in a Muslim area and were not allowed to spread our Christian message. He said he was going to take us to the police station.’
Mr Cunningham added: ‘I am dumfounded that the police seem so nonchalant. They seem content not to make it clear that what we were doing was perfectly legal. This is a free country and to suggest we were guilty of a hate crime for spreading God’s word is outrageous.’
According to a complaint by the men’s lawyers, Mr Naguthney summoned two other officers in support, one of whom, a full constable, is said to have told the men not to return to the area.
Mr Naguthney, 30, was recruited as a community support officer last year after being unemployed for eight months.
Earlier this year, he had a prominent role at a conference to launch the West Midlands branch of the National Association of Muslim Police. He gave a reading from the Koran before the audience heard a recorded contribution from Gordon Brown, a speech from Home Office Minister Tony McNulty, and contributions from several chief constables.
Mr Naguthney declined to discuss the row.
His brother, Nadeem, said: ‘Naeem is a community man, that is why he joined the police.’
The Alum Rock area was at the heart of a terrorism inquiry last year, which ended with the conviction of local resident Parviz Khan for plotting to kidnap and behead a British soldier.
A senior Church of England bishop, the Right Reverend Michael Nazir-Ali, warned recently that it is hard for non-Muslims to live and work in some areas where radicals and clerics are trying to impose an Islamic character.
A West Midlands Police spokesman said an investigation into the complaint had concluded that the PCSO had acted ‘with the best of intentions’ when he ‘intervened to diffuse a heated argument between two groups of men’.
A statement added: ‘Following this investigation, the PCSO has been offered guidance about what constitutes a hate crime and advice on communication style.’