DUP leader Ian Paisley was today facing growing pressure to explain his controversial lobbying in support of a Lottery grant bid by would-be Giant's Causeway visitor centre developer Seymour Sweeney.

The Belfast Telegraph revealed yesterday that Dr Paisley had fired an angry broadside at the Heritage Lottery Fund (HLF) in 2003 when it turned down a funding application for Mr Sweeney's Causeway centre project.

The DUP leader's letter said the businessman - who is a DUP member - had the support of world heritage body UNESCO for his scheme.

That has been disputed by a top UNESCO heritage official, Dr Mechtild Rossler, who today told the BBC that her organisation only deals awith proposals from Governments.

"We don't deal with private developers," she stressed.

Dr Rossler also said there was no question of her approving the businessman's plans.

"I can't. I'm not the body to approve anything there," she added.

Dr Paisley's letter to HLF's London headquarters was also fiercely critical of its grounds for refusing a grant - describing them as "absolute rubbish" - and threatened to raise the matter at Westminster.

It was written on House of Commons headed paper in Dr Paisley's name as MP, MEP and MLA.

It appears to have been signed on his behalf by his politician son Ian Paisley Junior, who has strongly supported Mr Sweeney on the Causeway and other business projects.

It said Mr Sweeney's "application as presented has UNESCO approval" and later added: "UNESCO saw and approved the plans and they were actually very impressed by the proposal."

The letter, obtained by this newspaper under freedom of information, has added to the "cronyism" row surrounding the DUP's Causeway stance.

SDLP MLA John Dallat today commented: "A detailed explanation is needed, preferably on the floor of the Assembly, on the claims made in this letter.

"This is a serious matter. It involves a senior public representative and his behaviour towards a public body over the use of what is effectively public money."

Alliance leader David Ford said: "Ian Paisley was entitled to lobby on behalf of his constituent and party member.

"However, it appears that the letter's claims are not consistent with UNESCO's position.

"Questions will have to be answered as to how the now First Minister has been handling this issue."

DUP Environment Minister Arlene Foster last month said she was "of a mind" to issue planning permission to Mr Sweeney's Causeway centre project. Environment chiefs in her department have recommended a refusal.

Mrs Foster has strongly denied being aware of the businessman's DUP ties when she announced her preliminary decision. She also said no one had lobbied her as Minister on the issue.

Sinn Fein MLA Daithí McKay has called for a "full investigation" into the whole Causeway centre controversy in the wake of yesterday's Belfast Telegraph report.

Above: The letter sent by Ian Paisley to the Heritage Lottery Fund in 2003 protesting at its decision not to grant-aid the Giant's Causeway visitor centre project tabled by developer Seymour Sweeney. UNESCO has categorically denied the claim in Dr Paisley's letter that it had approved Mr Sweeney's proposals.