Shareholders in Axis-Shield are continuing to snub the 460p-a-share bid from US healthcare giant Alere, and may be waiting for a better price.

Alere made its cash offer on August 5, after having an informal approach rejected earlier in the summer by the Scottish-Norwegian maker of diagnostic equipment.

Axis-Shield rejected the offer vigorously, with chairman John Brown calling it “opportunistic and wholly inadequate”.

Alere had received acceptances for only 1.03% of the shares it does not hold by the first closing date on September 1, and extended the offer for a further two weeks.

Yesterday, Axis-Shield said acceptances had risen over the fortnight from 471,116 to 498,654, a rise to just 1.09% of the shares.

Alere had not added to its own holding of 4.54 million shares or 9.09% of the share capital, however it said that yesterday, after the closing date, it acquired a further one million shares, taking its total to 11.09%.

It has extended the offer again, this time until October 10.

Axis, which employs a fifth of its 550 global staff in Dundee, maintains that the £230m offer “fundamentally undervalues” the company.

Some analysts had speculated that rival bidders might be flushed out, such as Abbott, Roche or Johnson & Johnson, who by acquiring Axis would provide tougher competition for Alere in the “lipid” market for measuring cholesterol levels.

Axis-Shield is about to launch its potentially lucrative lipid panel test in Europe later this year, and chief executive Ian Gilham has said the product positions the company in a $500m-a-year market.

Last month, Axis-Shield unveiled underlying pre-tax profits of £4.3m for the first six months of the year, a rise of over 50%.

But as yet no other bidder has emerged, and the Axis share price, which touched 490p last week on hopes of a higher offer, opened only just above the offer price yesterday, rising 1.5p on the day to close at 462p.

Observers, however, believe that Alere will not want to risk being outbid at this stage, and moreover that a higher price is one that the US giant can well afford to pay.

Analysts at DnB NOR Markets say that in previous acquisitions, Alere has similarly started with a low-ball price, and could be ready to up the offer by 10% to 20%.

Analysts at Investec have said “a fairer price would be between 530p and 570p”.