Middleton is considered a science success

Alan Heyward's comments came ahead of a crucial meeting of the garden's stakeholders to be held in Cardiff on Thursday afternoon.

Trustees, bankers and representatives of Carmarthenshire council and the Millennium Commission will try to devise a rescue package for the west Wales site, now called Middleton.

Mr Heyward also confirmed its overdraft was running at �1.9m - just �100,000 short of its limit of �2m.

Earlier, Culture Minister Alun Pugh Culture 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.

Money is on offer from the assembly for one month

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

But Mr Heyward called his refusal to change Middleton's status "unfortunate" and said the garden's trustees were not calling for a "bottomless pit" of money.

The trustees now have less than 24 hours to decide whether to accept �150,000 from the assembly to keep it open for a month while partners are sought for the project.

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.

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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.

The original project director of Wales' troubled botanic garden, William Wilkins, has given his support to transferring control of the site to a consortium of public bodies.

He told BBC Wales the original plan had not been seen through, but said the garden's quality justified "drawing a line" under what had happened and finding a solution to keep the garden open.