In sequences edited out by the BBC, the Labour front-bencher dismissed Prince Charles's role in attracting investment to Wales as "propaganda", and said he could not become king if he "stays living in sin" with Camilla Parker Bowles.
The new comments will heap more embarrassment on the Labour leadership, as John Major savaged Mr Davies for saying the prince was not fit to be king - while Labour left-wingers rallied to his defence.
On Friday the shadow minister issued an abject apology over his attack on Prince Charles, which he made in an interview on BBC Wales's Welsh Lobby programme.
In the unbroadcast segment, Mr Davies says bluntly: "I am a republican." Asked about the claim that Prince Charles has brought much investment to Wales, he replies: "I don't believe that. It's just propaganda." He added: "Charles cannot be king if he stays living in sin with Camilla."
Yesterday the BBC said the comments had been edited out as part of normal production. A spokeswoman said: "The film was edited to concentrate on what we presumed to provide the best news value."
The Labour leadership, although angry at Mr Davies's outburst, was standing by his decision not to resign. Tony Blair is said to feel that it was the intemperate tone of the MP's comments, rather than his republican sympathies, that had provoked most embarrassment.
The Conservatives moved swiftly to exploit the gaffe and to present it as part of a Labour assault on the British constitution.
Mr Major, speaking in Bangkok, said: "I am absolutely astonished that somebody who is in the Shadow Cabinet, and who would presumably be the Welsh Secretary in a Labour administration, can speak in this fashion, particularly about someone who cannot answer back. I think most people will regard that as a pretty distasteful." William Hague, Secretary of State for Wales, called for Mr Davies to be sacked.
Labour left-wingers, however, defended him. Ken Livingstone, MP for Brent East, said a "large number" of Labour MPs privately agreed with Mr Davies's view - and he accused Mr Blair of looking "panicky" by making Mr Davies apologise.
The veteran left-winger Tony Benn said Mr Blair had been rough on the MP, particularly as the Labour leader himself had recently said hereditary peers should not sit in the Lords. "What Mr Davies said was that hereditary monarchs should not be heads of state. It's very similar, and there is a very strong body of opinion now in Britain in favour of a democratic constitution."
Last night MP Tony Banks called for a nationwide poll "when the present Queen gives up her time on earth" to decide whether Britain should continue to have a hereditary head of state.
The Prince of Wales left for a skiing trip in Switzerland without commenting. "Mr Davies has withdrawn his remarks," said a Buckingham Palace press officer. "He has apologised and, as far as the Prince of Wales is concerned, that's the end of it."
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