Oberthur said it was disappointed that De La Rue's board had "so swiftly rejected" its increased proposal, of 935p per share, which the French firm believed to be "full and fair".

Jean-Pierre Savare, president of Oberthur, said: "Our increased proposal offered compelling and immediate value and was backed by our debt and equity partners.

"We have repeatedly sought to enter into constructive discussions with the board of De La Rue over the past four months and we believe our approach could have offered a much-needed catalyst to restore De La Rue's reputation.

"The Board of De La Rue has not only rejected our approach but has also ignored requests for clarity to be given to the market in relation to fundamental questions about the company's customer relationships and financial prospects.

"As a result, De La Rue shareholders have seen no information to support De La Rue's assertion that the increased proposal significantly undervalues 'the strong fundamentals of the company and its long-term prospects'."

Oberthur and De La Rue have been at odds over their respective valuation of the company from the outset, when De La Rue's board refused to enter discussions with Oberthur following its 905p per share indicative offer.

In an increasingly heated war of words, De La Rue has repeatedly stated that it does not believe Oberthur's offer(s) are representative of the true value of the world's largest banknote printer. Oberthur has countered that in light of the reputational impact of De La Rue's troubled year, it is the latter's valuation which is inaccurate.

In presumably its final statement to the stock exchange on its failed takeover bid, Oberthur said: "Bearing in mind the significant difficulties being encountered by De La Rue and the structural changes occurring in the global banknote paper market, shareholders in De La Rue may now ask themselves how long it will be before the market price of De La Rue shares attains the level of the increased proposal."