The Church of England has warned clergy that they may be subject to disciplinary measures if they support or join the British National Party.
The ban, which also applies to membership in the National Front, comes a week after a disastrous Euro-elections for the BNP in which party leader Nick Griffin lost his seat.
It permits a complaint of misconduct to be brought against any cleric who is a member of or "promotes or expresses or solicits support for the BNP or NF".
It is understood to be the first ban of its type in the Church of England on clergy party membership and has been put forward by the House of Bishops in response to a request from Vasantha Gnanadoss at the 2009 General Synod. Her request for a ban similar to that in place for police officers met with resounding approval by the Synod.
In their declaration issued today, the bishops agreed that the constitutions, policies and objectives of the BNP and NF are "incompatible" with the teaching of the Church of England "in relation to the equality of persons or groups of different races".
The declaration will come into force at 5:30pm on 11 July, during the York meeting of the Church's General Synod, unless 25 Synod members request a debate. If this happens, the declaration would need to be approved by Synod before it could come into effect.
"Once a declaration comes into force support for the political party concerned by clergy of the Church of England would be unbecoming or inappropriate conduct," the Church of England said in a statement.
Simon Darby, former deputy leader of the BNP, was dismissive of the ban in comments to The Telegraph.
He claimed some Anglican clergy were members of the party and that their supporters included members of the Church of England's General Synod.
He suggested the ban on BNP membership was more about the "politicisation of the church" by people who are "more interested in neo-marxism".
"These are people that don't bother teaching the Bible, they are more interested in being politically correct," he said.
"Where is it going to end? Am I, because I am a member of the BNP not going to be buried on church ground?"