The organisations, which in the past might have feared the consequences of Labour policy, are now being invited to contribute. For example, McDonald's is believed to have made representations recently on the minimum wage.
At a seminar last week in the party's Millbank headquarters, Tony Blair's Parliamentary Private Secretary, Anne Coffey, and the head of the Labour Party Policy Unit, Margaret Mythen, explained policy-making in the party and how it interacts with government.
Those invited were told they would gain a "unique opportunity to discuss and gain an understanding of our new policy development process", Afterwards, they were invited to attend seminars on issues such as health, home affairs, trade and industry and the economy.
They have also been invited to a "special corporate event" at this autumn's party conference in Blackpool. This includes reserved tickets for Tony Blair's speech, seminars and discussion groups on policy and a reserved place at the conference gala dinner. Last year's package cost pounds 750.
The list of those in attendance at a policy seminar last week - described on the invitation as "corporate affairs executives and representatives of public affairs companies" - included Tesco, Railtrack, the Post Office, British Airways, the Food and Drink Federation, National Westminster Bank and The Stock Exchange.
Those who attended were also invited to buy into the "Labour Party Policy and Information Service," through which they can receive papers relating to the new National Policy Forum, which will shape the party's manifesto for the next election.
Michael Prideaux, director of group public affairs for British American Tobacco, said the seminar was attended by a representative of its financial services businesses because the cigarettes it made in Britain were all sold abroad. They would have been particularly interested in the reform of the Welfare State, he said.
"The point about policy-making is always to be able to discover what is being contemplated early enough in order to contribute to it," he said.
Others were unimpressed, though. A senior trade union source said the links were bound to cause a conflict of interest, with the demands of business leading to a watering down of party policy.
"The more money they get from other people, the less they need from us. And the less they get from us, they less they need the link with us," he said.
A Labour spokeswoman said the National Executive Committee had given its full support. The party wanted all types of organisations, including trades unions and voluntary groups, to play a part in policy-making.