The glasshouse at the National Botanic Garden of Wales

The cash will cover operational costs and a new marketing drive to attract more visitors.

But critics, who have dubbed the attraction Wales' Millennium Dome, say the �43.3m project should not be subsidised with any more public money.

In September 2002, the assembly provided a grant of �360,000 while a full review of the financial situation at the Llanarthne garden was undertaken.

Announcing the extra funding on Wednesday, Culture Minister Jenny Randerson said the money would help the garden develop over the next six months.

"The garden is a landmark project for Wales and is a significant factor in the tourist economy of south west Wales," she said.

"It provides a unique experience in Wales, and is the first botanic garden to be created in the UK for over 200 years.

Wales now has its own Millennium Dome - if it is not going to pay its way, then let's shut the thing down Ashford Price, National Show Caves

"We will work closely with the garden and public sector partners to ensure the garden's future," she added.

Middleton - as the botanic garden is now being dubbed - was opened by Prince Charles in 2000 and is run by a charitable trust.

In its first year, it attracted 220,000 visitors but numbers have fallen and it is predicted the garden will have attracted around 175,000 at the end of year three.

Communications manager Owen Jenkins said the money would see the attraction through a vital stage in its development.

"This is a vote of confidence in south west Wales and in the dedicated staff and volunteers who work here," he said.

"As a charitable, not-for-profit organisation, this support is enabling us to drive forward our ambitions and will allow us to sustain a strong, solid base for future success.

"We are investing in a new marketing presence, to lay the foundation for future development and increase our income generation," he added.

Distorted market

However, Ashford Price, who owns the National Show Caves in the Swansea Valley, said private tourism operators could not compete against subsidised attractions.

Visitors at the garden

He also said the scrapping of entry fees to museums and galleries had had an effect on business.

"It distorts the market place to such an extent that private operators just cannot compete," he said.

"Wales now has its own Millennium Dome - if it is not going to pay its way, then let's shut the thing down."

But Huw John, cabinet member for regeneration with Carmarthenshire Council, said the garden played an important role in the county's tourism industry.

"The investment is excellent news for the garden which is a vital part of Carmarthenshire's tourism industry," he said.

"The botanic gardens in England and Scotland are publicly supported so it's only right and proper that this one is as well," he added.