DUBLIN — A well-known Irish Catholic priest plans to defy Vatican authorities on Sunday by breaking his silence about what he says is a campaign against him by the church over his advocacy of more open discussion on church teachings.

The Rev. Tony Flannery, 66, who was suspended by the Vatican last year, said he was told by the Vatican that he would be allowed to return to ministry only if he agreed to write, sign and publish a statement agreeing, among other things, that women should never be ordained as priests and that he would adhere to church orthodoxy on matters like contraception and homosexuality.

“How can I put my name to such a document when it goes against everything I believe in,” he said in an interview on Wednesday. “If I signed this, it would be a betrayal not only of myself but of my fellow priests and lay Catholics who want change. I refuse to be terrified into submission.”

Father Flannery, a regular contributor to religious publications, said he planned to make his case public at a news conference here on Sunday.