The Archbishop said that those that refused to sign the doctrine would be excluded from full membership of the Church and would instead become "associates". It would mark the most significant shift in the Anglican Church since it was created in the Reformation.Dr Williams, in a letter to the primates of the 37 other Anglican provin-ces, said: "There is no way in which the Anglican Communion can remain unchanged by what is happening at the moment. Neither the liberal nor the conservative can simply appeal to a historic identity that doesn't correspond with where we now are."

Those liberal provinces which refuse to agree with the doctrine will have equivalent status to that of the Methodists, a Protestant Church in communion with and recognised by the Church of England but not part of it.

Conservative parishes and dioceses in the United States have already indicated that they want to sign up to the covenant, but they are in the minority. They are expected to urge the Archbishop of Canterbury to accept their own network as a separate, constituent province of the communion, effectively splitting the US Church in two.

Some liberal parishes and dioceses in the Church of England will oppose the proposals because they want to see the Church follow the radical revisionist route seen in America. The Archbishop wrote the letter in response to the meeting this month of the General Convention of the Episcopal Church of the United States of America which failed to resolve the crisis surrounding the consecration of the openly gay Gene Robinson as a bishop in 2003. The convention rejected a motion that would have brought the Episcopal Church close to compliance with the demands of the Windsor report that had been published by a group set up by Dr Williams.

The Archbishop said: "What most Anglicans worldwide have said is that it doesn't help to behave as if the matter had been resolved when in fact it hasn't." The proposals amount to a two-track Anglican Communion, with conservative churches on the inside track and pro-gay liberals on the outside. The covenant would make it impossible for any province in future to act against the will of the majority. Churches that refused to sign up could opt to cut ties to Canterbury or remain in associate status.

The proposals will be discussed at the next meeting of the standing committee of the 37 primates and then at the primates' meeting in February. They will be discussed by the worldwide Church at the Lambeth Conference in 2008.

Canon Chris Sugden, the executive secretary of the Anglican Mainstream grouping, said: "The Archbishop's letter rightly recognises the priority of Scripture and that the Church must respond on the basis of the Bible and historic teaching rather than cultural or rights-based views."

Liberals gave warning against the creation of a two-tier Church. The Rev Richard Jenkins, the director of Affirming Catholicism, said: "If a formal covenant is intended to help us to live in solidarity with each other then it must function in a dynamic way, not simply acting as a brake on every development."

The Rev Mark Harris, an episcopal priest of the Delaware diocese and a deputy to General Convention, quoted the Declaration of Independence and said: "General Convention 2006 will go down in history, among other reasons, for the clarity with which the Church of England has attempted to exercise direct and indirect ecclesiastical colonial control."

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