Middleton is considered a science success

William Wilkins said the original plan had not been seen through, which had led to some of the financial problems the garden, now known as Middleton, faces.

However, his comments came just before Culture Minister Alun Pugh definitely ruled out changing the garden's status and giving it the same type of backing as the National Museums and Galleries of Wales.

BBC Wales has been told he will also not bow to mounting pressure to bail out the cash-strapped gardens.

He is understood to believe spending the millions involved could never be justified to Welsh taxpayers.

The essential thing is that we release the marvellous potential of what's been achieved and what could be achieved William Wilkins

The board of trustees at the west Wales site has less than 24 hours to decide whether or not to accept an offer of �150,000 from the assembly government to keep them open for a month.

Speaking to BBC Wales, Mr Wilkins, who was responsible for the original conception of the garden at Llanarthne, agreed that the tourist element at the garden was missing.

Asked if the original plan was flawed, he said: "I think the plan has not been realised.

"[What's missing is] some of the great restoration elements which were designed to complement the scientific and educational role of the garden and the contemporary role."

He argued more money needed to be spent now in order for the garden to pay its way in the future and said the quality of the garden justified "drawing a line under the present situation".

"I don't see why any management arrangement shouldn't be considered because the essential thing is that we release the marvellous potential of what's been achieved and what could be achieved.

"If it ensured its future, I think a consortium of other bodies [to run Middleton] would be entirely acceptable."

Some of the bodies in question include the University of Wales and the National Museums and Galleries of Wales.

The money will keep Middleton's gates open for another month

On Tuesday - the day funds at the garden ran out - finance minister Sue Essex offered the garden money to keep it open for a month following a meeting of the trustees.

She said the cash would allow time to possibly find partners for the garden to enable it to remain open.

A row broke out between the assembly and the board, who claimed the terms put impossible conditions on the trustees, specifically that they would be liable to repay the money if the garden did fold.

But the First Minister's office denied this, saying they would have "no recourse" to reclaim any cash.

Speaking in the assembly's economic development committee on Wednesday, minister Andrew Davies reiterated the assembly government's wish to keep the garden open while a partner was sought.

He denied the government had abandoned the garden and said discussions about Middleton's future were ongoing.