Dr Carey said: "By restating the long-held view of the Roman Catholic Church on the position of other Christian churches, this document breaks no new ground.
The Dominus Iesus declaration, which has been written by a close aide of Pope John Paul II, says that the Roman Catholic church is the "mother" of all Christian denominations and that it is incorrect to refer to the Church of England and other Protestant churches as "sister" organisations on a par with Rome.
The Archbishop of Canterbury, Dr George Carey, said the document risked pouring cold water on decades of progress in bringing different churches closer together.
Dr Carey said: "By restating the long-held view of the Roman Catholic Church on the position of other Christian churches, this document breaks no new ground.
"But neither does it fully reflect the deeper understanding that has been achieved through ecumenical dialogue and co-operation during the past 30 years.
"Even though the document is not part of that process, the idea that Anglican and other churches are not 'proper churches' seems to question the considerable ecumenical gains we have made."
The declaration, written by Cardinal Joseph Ratzinger, is due to be sent to every Catholic bishop in the world.
'No slight intended'
The term "sister churches" is often used in dialogue aimed at fostering closer ties among Christians.
The Pope has made steps toward unity with other Christians, a key goal of his papacy in Christianity's third millennium.
But Cardinal Ratzinger, the Vatican official in charges of ensuring doctrinal correctness, is quoted in the document as saying that considering the Catholic church as one way of salvation alongside those represented by other religions, is going "against the faith".
"The main purpose of the Vatican's declaration is to warn against a tendency to regard all religions as equivalent.
"It is written principally for Catholic bishops and theologians."
He denied the document damaged in any way the Catholic church's ecumenical approach.
"As Christians we share a common baptism and the Catholic church believes this brings us into a real, if imperfect, communion.
"This was made clear in the documents of the Second Vatican council, where it said that other Christians 'with good reason are accepted as our brothers and sisters'.
"This new document does not attempt to change the teaching of the Catholic church regarding ecumenism."