Banknote printer De La Rue has rejected an improved offer from French rival Oberthur.Oberthur increased its offer for De La Rue to 935p from 905p previously, but De La Rue said that this "continues to undervalue significantly the strong fundamentals of the Company and its long term prospects."Chairman Nicholas Brookes said that, having appointed a new chief executive, Tim Cobbold, to lead a restructured management team, De La Rue is confident that it has a promising future."My first few weeks at De La Rue have confirmed my view that De La Rue is a high quality business with substantial potential in growing markets," said Cobbold. "There are, of course, opportunities for improvement, building on changes already made, but shareholders should be in no doubt of my absolute commitment to realise De La Rue's full potential and deliver significant value."Shares in De La Rue plunged last year after news emerged of production problems that are believed to have affected its biggest client India.Oberthur has been putting pressure on De La Rue to provide more detail about the production problems and their consequences.Earlier this month it said that it "has reason to believe that the most recent tender for the supply of 16,000 tons of currency paper by the Reserve Bank of India has been awarded to four competitors of De La Rue, and not to De La Rue."