Shares in De La Rue were soaring on the FTSE 250 in morning trading after the banknote printer confirmed that it had received a takeover bid.
While De La Rue did not name the bidder, it is believed to be French firm Oberthur Technologies.
De La Rue described the bid as "highly preliminary and opportunistic" and added that there was "no certainty" that the bid would lead to a final offer.
The group said it would make a further announcement when appropriate.
By 08:50 shares in De La Rue were up 25.25 per cent on the FTSE 250 to 811.00 pence per share.