David Hunt, the Secretary of State for Employment, said he would comply but some of the other 12 Tory MPs were adamant they would not divulge the details, which could allow accurate estimates to be made of their losses as names.
Michael Colvin, Tory MP for Romsey and Waterside, said he had given details of his syndicates to the registrar of members' interests, but on instructions that they should not be published.
'They must register. If they don't, they will be a hell of a row,' said Angela Eagle, a Labour member of the committee on members' interests. She said it was 'not good enough' to give details in sealed envelopes of syndicates. The committee urged the 12 Tory MPs to 'comply without delay'.
The rule cannot be changed without a vote on the floor of the Commons. Labour MPs will provoke the row at the next meeting of the committee by formally lodging a complaint about the failure to comply with the rules.
Others who failed to comply, included Sir Edward Heath, the former Prime Minister, and Richard Needham, a Minister of State for Trade.
The controversy over MPs' business interests continued as the new register revealed that Ann Taylor, a member of Labour's Shadow Cabinet, is a paid director of a company that lobbies parliament on behalf of clients along with two Tories and a Liberal Democrat MP.
Other directors of the same 'public affairs' company - Westminster Communications - are Menzies Campbell, a senior Liberal Democrat, and the Conservatives Sir Marcus Fox and Sir Keith Speed.
The involvement of Ms Taylor, Labour's education spokeswoman, in a lobby company has infuriated some Labour MPs who see the connection as an embarrassment to the party.
Ms Taylor, who with Mr Campbell was invited to join the lobby company last summer, said: 'There is no official Labour Party campaign against MPs being involved with lobby companies. I am sure none of my colleagues would see any conflict of interest when my clients with Westminster Communications are the Foundation for Sport and the Arts and the Commission for Racial Equality'.
Mr Campbell said: 'I agreed to join the company only on the basis there would be no conflict of interests between my responsibility to my constituents and my party.'
Sir Keith said: 'Ann Taylor and Menzies Cambell are in a position to provide strategic advice on Labour and Liberal Democrat thinking in particular areas. We are all very friendly and absolutely professional'.