Sir Tom Hunter is expected to raise his stake in garden centre operator Dobbies to nearly 30% in his continuing share-buying battle against Tesco.

Sir Tom disclosed yesterday that he had bought 90,000 more shares, taking his stake to 27.66%, a day after Tesco revealed it had raised its stake to 29.9%.

It is understood that under Takeover Panel rules neither side can raise their stake above 29.9% and so Tesco will need to get the backing of independent investors if it is to gain control of the company.

The supermarket needs the support of investors representing 50.1% in order to make its bid unconditional. Including the shares it now owns, Tesco's acceptances amount to 34.4% and investors have until 19August to accept the supermarket's offer.

Dobbies shares fell 25p to £14.75 yesterday as most remaining investors appeared ready to accept Tesco’s offer.