Profits have been disappointing since Porton was set up in 1982 - about pounds 3m on turnover of pounds 49.1m in 1992 - though business is thought to have improved.
Gordon Duncan, of Kleinwort Benson, the merchant bankers recently engaged to promote the company, said several potential purchasers or partners had made approaches.
Porton is owned by 44 institutional shareholders, including Sun Alliance and Legal and General, and Wensley Haydon-Baillie, the founder and former chairman who still has about one-third of the company. Porton makes vaccines and markets drugs for leukaemia and muscular problems.
In 1985 it forecast profits of pounds 140.6m in 1990. But it suffered from reputations for secrecy and high executive salaries.Reuse content