A controversial organisation of businessmen which donates money to the Conservative Party has relented to pressure and named its members.
Sir Anthony Bamford, left, with David Cameron in India last month
The Midlands Industrial Council (MIC) said it had named its members in the "interests of transparency".
They include Robert Edmiston - quizzed in the "cash-for-honours" inquiry - and JCB boss Sir Anthony Bamford.
Labour had called on the Conservatives to name those involved and urged the Electoral Commission to investigate.
MIC secretary David Wall said: "Following two weeks of consultation with members and whilst we are under no legal obligations to do so, in the interests of transparency, the council has decided to issue a list of its members."
He said the MIC complied fully with the Political Parties, Elections and Referendums Act 2000.
The MIC said it had published an "exhaustive" list of its 22 current members.
Sir Anthony Bamford
Lowe & Fletcher Ltd
G Hampson Silk
It includes IM group head Robert Edmiston, who lent the Tories £2m before last year's general election but has since converted the loan into a donation, was questioned by police in July.
Another MIC member, John Butcher, 60, was MP for Coventry South West from 1979 until 1997 and is a former schools minister.
Mr Wall said anyone who refused to be named would have been asked to step down, but that none did so.
He said the group did not have any accounts to publish because it did not need to keep any.
A Conservative spokeswoman said: "David Cameron strongly supports the move towards greater transparency and we warmly welcome the decision by the MIC to publish its list of members.
"We hope for continued transparency in the future."
But Labour Party chairwoman Hazel Blears said: "The Conservative Party must first disclose whether this is the full list of all people who have donated to the Conservative Party campaigns through the shadowy Midlands Industrial Council.
"Is this really an exhaustive list of all members who have given donations to the Tory party through the MIC? Have the Tories really come clean or are there more names to be exposed?"
The MIC is also reported to give about £1m a year to a company called Constituency Campaigning Services (CCS) which supports Tories in key marginal seats.
The Conservatives have said CCS is independent although earlier this month Mr Cameron told BBC One's Sunday AM programme it was "effectively a part of the Conservative Party".
The Electoral Commission said that after a recent flotation CCS was "owned by the party" but no longer "part of the party".
The commission's register of donations shows the MIC donated £968,689 directly to the Conservative Party over the past three years.