A bidding battle would be good news for Boots shareholders

The Wellcome Trust and private equity group Terra Firma are understood to have asked to see the books of Britain's biggest pharmacy chain.

It is rumoured that Celesio, the German owner of the Lloyds pharmacy chain, is also considering an approach.

KKR upped its offer last month after an earlier bid was dismissed as too low.

Alliance Boots has now opened its books to the potential buyer, which had teamed up with Boots' Deputy Chairman Stefano Pessina, who already owns 15% of the retailer.

A decision on whether Wellcome and Terra Firma will be allowed to see the books is expected by Friday.

High profile

The Wellcome Trust is Britain's biggest charity as well as the country's largest investor in private equity.

Terra Firma is run by the high profile financier Guy Hands and owns the Odeon and UCI cinemas, among other investments.

Alliance Boots is best known in the UK for its 2,600 Boots the Chemist shops on the High Street.

But since its �7bn tie-up with Alliance UniChem last year it is now also a major drugs wholesaler, with a 40% market share, supplying more than 125,000 pharmacies, health centres and hospitals.

Mr Pessina is believed to want to take the company private and grow it away from the public spotlight.

But trade unions have warned that selling the group to a private equity firm could lead to asset-stripping.