Jefferson Smurfit may be lining up a takeover bid for the publicly-quoted British packaging company, Norcor Holdings - a bid that would probably cost the company more than £20 million. Norcor disclosed yesterday that SGH, a Smurfit subsidiary, bought a further million shares on Wednesday, taking its stake in the Norwich-based company to 6.8 million shares or 25.4 per cent.

The Smurfit subsidiary has been buying up small amounts of Norcor stock in the past year, but since the beginning of this month Smurfit has taken its stake from 10 per cent to 25 per cent. A spokesman for Smurfit would make no comment on the stakebuilding in Norcor, but industry analysts believe that Smurfit is probably gearing itself up for a bid.

Norcor shares fell 2p yesterday to 72p sterling, valuing the company at just under £20 million sterling. Norcor has gone through a difficult period over the past two years, and that 72p closing price compares with a 99p high and a 65p low in the past 12 months.

Norcor is one of Britain's biggest manufacturers of corrugated sheet board and its business would fit in snugly with Smurfit's existing British operations which are largely based on its Townsend Hook packaging operations. Smurfit does not provide details of its British operations, which are combined with Ireland for reporting purposes.

Last year, difficult trading conditions resulted in a sharp fall in sales and profits for Norcor, with sales falling from £55.9 million sterling to £46.3 million sterling, and pre-tax profits more than halved from £2.6 million to £1.2 million. An improvement in the first half of this year saw Norcor increase pre-tax profits from £350,000 to £750,000.

In a statement with those half-year results, Norcor chairman David Snelden said that sales and market share had fallen in the first half of 1997, while the strength of sterling had also cost the Norwich based group £300,000 in lost profits.