US private equity firm KKR has joined forces with Stefano Pessina, deputy chairman and largest shareholder in Alliance Boots, to make a £10-a-share cash takeover approach for the retailer.

The offer values Alliance Boots at £9.67 billion (€14.25 billion).

KKR is also part of the consortium considering a bid for J Sainsbury.

In a statement, KKR and Mr Pessina said: "The proposal requires, inter alia, limited due diligence being satisfactorily completed, which we anticipate will take three weeks after full information is made available, and a recommendation from Alliance Boots's board to Alliance Boots shareholders to accept the offer."

Shares in Alliance Boots jumped yesterday afternoon after the group, which is Britain's biggest pharmaceutical retailer, said it had received an approach about a possible takeover.

In a statement, the group said it had received "a preliminary and highly conditional approach regarding a possible offer".

However, the retailer did not identify the suitor and it said there was no certainty that an offer would be made.

Alliance Boots shares closed 115p or more than 14 per cent higher at 930p, valuing the group at £8.9 billion.

The group, formed last year by the £8 billion merger of Boots and Alliance Unichem, operates about 2,600 chemists across the UK.

It operates another 400 stores in other parts of Europe and in Thailand.

The group's wholesale arm serves more than 125,000 pharmacies, hospitals and clinics in eight countries.

The Boots chemist chain has about 40 stores in Ireland and plans to increase the number to 70 by 2011.

Its outlet in Grafton Street, Dublin, produces the highest return per square metre of any store in the Boots chain, while over the Christmas period, its Liffey Valley store takes in more money than any other Boots store worldwide.

Alliance has a presence in the North, where it acquired the 50-strong Baird chain in 2004.

In January it announced plans to enter the Chinese market through a joint venture with Guangzhou Pharmaceuticals Corporation, the country's third-largest pharmaceutical wholesaler.

The company had been due to provide a trading update on March 30th.

In January, Boots said it had seen an unexpected slowdown in revenue growth at the group's British stores in the Christmas trading quarter.

The group also said that revenue had been hit by a cut in the amount that the British government reimburses the company for dispensing generic prescription drugs.