The group said the approaches were at an early stage, and might lead to an offer for the company at a significant premium to its current share price.

Shares in the Wetherby-based group rocketed 38 per cent on the news of a potential bidding battle, to close at 94.25p.

Investment firm One51, a Dublin-based group with stakes in environmental companies across the UK and Ireland, said it is one of the firms which had approached Augean. One51 revealed it owns and controls 26.9 per cent of Augean with its 17.6m shares.

In a trading update Augean, which employs more than 200 people across its 11 sites, added its waste treatment division was "performing well and is continuing to provide much potential for the future."

The group said for the first time Augean was starting to see a "considerable, sustained upturn in activity" at its hazardous waste landfill sites.

In 2006 it warned its landfill business was going to take longer than hoped to reach its potential. It blamed this on problems in regulation and enforcement.

"Whilst this has been frustrating for all concerned, we have maintained our belief in the long-term strategic value of Augean's unique landfill assets as an important part of the solution for effective waste disposal in the UK," it said yesterday.

Augean said it had reached agreements with "certain large customers" for its landfill business, and its treatment business was performing in line with expectations.

As a result of this, Augean said it was confident market expectations would be achieved, and could even be exceeded. It will make an announcement on the bid approaches when appropriate, it said.