An Anglican parish priest is among eight religious protesters strip-searched by WA Police after a peaceful demonstration at Foreign Minister Julie Bishop's office.

The group, from the Love Makes a Way campaign drawing attention to asylum seekers in detention, is drafting a complaint to the Corruption and Crime Commission about their treatment on Wednesday evening.

The Rev. Lorna Green, 59, parish priest at Serpentine Jarrahdale and part-time Department of Corrective Services prison chaplain, said the protesters were stripped naked at Perth Watch House and told to "squat and cough" during searches.

The group's lawyer Shash Nigam said police usually strip-searched only those they reasonably suspected could be carrying a weapon, firearm, ammunition or drugs.

"I felt humiliated," Ms Green said.

"I was outraged. I said to the police, 'You know this is totally unnecessary. I'm a grand- mother, for goodness sake'."

Five women and three men, including a Uniting Church minister and pastors from the Church of Christ and Pentecostal Church, have been charged with trespassing and will appear in court this month.

The group want the Federal Government to abandon plans for 25 babies born to asylum seekers in Australia to be transferred to detention in Nauru.

Ms Green said the group were treated respectfully by Ms Bishop's Subiaco electorate staff and initially by officers, but late in the afternoon WA Police told them they would be strip-searched and acquire a criminal record if they did not leave.

Two weeks ago, a similar sit-in by female religious leaders at Senator Michaelia Cash's office resulted in move-on notices and a protest at Ms Bishop's office in April resulted in arrests and trespass charges but no strip- searches.

A WA Police spokeswoman said officers negotiated with the group for more than an hour to leave. "The group were fully advised they would face charges and as such undergo standard procedures at the Perth Watch House if they did not comply," she said.

Uniting Church of Australia WA moderator, the Rev. Steve Francis, said WA Police had "deliberately humiliated people engaged in a peaceful act of civil disobedience".

"Strip-searching is an outrageous and offensive response to Christian concern for the vulnerable, and I will be seeking an urgent explanation from the WA Police Commissioner," he said.