Two more plots on the Ashdown Business Park, near Uckfield, are under offer, according to commercial agents Lawson Commercial.
A German company presently in West Sussex is interested in combining the two sites – making a total of two-and-a-half-acres – but a change of planning consent will be needed to alter the style of a building already approved.
Lawson Commercial partner Chris Lawson said a planning application was likely to go in to Wealden Council early in the New Year.
The sites are numbers six and seven, next door to where a new headquarters is being built for Swedish safety equipment supplier Gunnebo, and one site away from the John Lewis distribution centre.
Mr Lawson said the German company is seeking 20,000 sq ft of offices and storage space.