LONDON – A priest who regularly conducts Mass for Prime Minister Blair and his family refueled speculation yesterday that the prime minister intends to become a Roman Catholic.

The Reverend Timothy Russ, whose parish includes Chequers, the prime minister’s official country house, disclosed that Mr. Blair, an Anglican, had raised the question of conversion with him and said: “If you ask me do you think he wants to become a Catholic, I would say yes.”

Rev. Russ indicated, however, that he did not believe that Mr. Blair would take such a step while the prime minister and suggested that he had “some way to go” on important moral issues.

Mr. Blair, a High Church Anglican, regularly attends Mass at Chequers with his wife Cherie and three children, who are Catholics, and he took part in a private service in the Vatican during a recent visit to Rome.

He has quelled speculation that he might become Britain’s first Catholic prime minister by insisting that has no plans to convert, and has said that he only goes to Catholic services so that he and his family can worship together.

But he has worshipped on his own at Westminster Cathedral and has been criticized for breaching Canon law, which states that except in exceptional circumstances, a non-Roman Catholic should not receive Catholic communion.

Rev. Russ, the parish priest of the Immaculate Heart of Mary in nearby Missenden, Berkshire, told a newspaper that Mr. Blair had raised the issue of conversion over lunch.

“When he asked me, it was in the abstract,” the priest said. “It wasn’t ‘Can I become a Catholic?’ but ‘Can the Prime Minister of Britain be a Catholic?’

He said that Mr. Blair would be “freer to consider the matter” after he had left office. “But even if he resigns or whatever, I doubt he has the ‘necessary’ to join the Catholic Church.

“It is always a work of grace,” said Rev. Russ. “He would probably have a lot going for him, but he also has to change a lot.”

The Catholic Church declined to comment, but Rev. Russ’s disclosure of private conversations with Mr. Blair will have dismayed senior churchmen as they expect priests to be discreet.

Downing Street also refused to be drawn, although a spokesman said the matter was a private one. But the disclosures are fresh evidence that Mr. Blair, possibly the most religious holder of the post since William Gladstone, has a growing fascination with the Catholic faith. Much of his political philosophy has been influenced by the social teachings of the Church, although he is also an admirer of the maverick German theologian Hans Kung, who has repeatedly clashed with the Vatican.

Francis Beckett, one of the authors of a new biography about him, the Blairs and Their Court, claims that he is, in effect, a Catholic already.

Although Britain has never had a Roman Catholic prime minister, there is no constitutional bar to Mr. Blair converting while in Downing Street.

However, constitutional historians have said that such a development could prove awkward and could affect the relationship between Church and state. As prime minister, Mr. Blair makes recommendations to the Queen on the appointment of Church of England bishops. Church spokesmen insisted, however, that this was a State rather than religious duty, and the prime minister’s religious affiliations need not be a difficulty.