A statement from the Assemblyman confirmed a connection between the businessman and DUP-run premises at 9-11 Church Street, Ballymena.

But the junior Minister said the link only lasted "weeks" and no rent was paid to Mr Sweeney.

MLAs receive rental expenses for their constituency offices from the Assembly.

The Church Street building became the new north Antrim office of Mr Paisley Jnr last summer.

It is owned by a company called Sarcon (no 250). Its official returns to Government's Companies Registry record that Mr Sweeney was appointed a director of the firm in May last year.

They further state that Sarcon (no 250) obtained a mortgage from the Bank of Ireland for 9-11 Church Street, Ballymena in July 2007.

In a statement last night, Mr Paisley Jnr said: "I can confirm that a company called Sarcon 250 owns the DUP office at 9-11 Church Street and has done since the summer of 2007.

"During the run-up to the purchase, for a period of weeks, Mr Sweeney as a member of the DUP gave advice on the purchase of the office and became a director of the company to ensure that the purchase could be completed.

"He subsequently resigned before any rent was due under the lease, in favour of a new director, as it was never intended that he would have any further role or be in receipt of any benefit."

The junior Minister further said that the rent expenses since claimed for the office were based on their then current market value, as advised by a professional agent. He also said the arrangement was "validated" by the Assembly.

The current online returns for Sarcon (no 250) at the Government's Companies Registry do not include any reference to Mr Sweeney's resignation.

Last night's statement by the MLA also referred to the Church Street office as part of the DUP's "long-term commitment" to north Antrim, indicating that it is party-owned.

Mr Paisley Jnr has faced criticism over his lobbying in support of the businessman on issues including a Government land sale at Ballee, Ballymena and Mr Sweeney's plans for a Giant's Causeway visitor centre development.

The controversy was heightened by the fact that Mr Paisley Jnr replied " I know of him" last September when asked by a radio presenter if he was supporting the property tycoon.

It soon emerged that the businessman was a DUP member and had sold a house to the MLA near Bushmills. It was emphasised that this sale was at full market value.

The politician has maintained that he has every right to speak up for a businessman in his constituency.

Following a freedom of information request by this newspaper, the Assembly is due to release figures next week on rental expenses claimed by each MLA. Details of landlords are not expected to be disclosed.