De La Rue has abandoned its challenge to Britain's decision to award the contract for new blue post-Brexit passports to a European firm and issued a profit warning today. 

Its shares fell 9% to a year low of 446 pence at one stage today after De La Rue said it would write-off about £4m of costs associated with the failed bid. 

Together with delays in some contracts in the last week of its financial year, this would result in it missing profit expectations, De La Rue said in a statement. 

British Prime Minister Theresa May said the decision to change British passports from the burgundy shade used by most European Union countries to the traditional dark blue was an expression of British independence and sovereignty. 

But reports that Franco-Dutch firm Gemalto had won the tender to produce the new passport was criticised by some politicians and newspapers as unpatriotic, and De La Rue had said it would challenge the decision. 

De La Rue prints 7 billion banknotes and 15 million passports a year.

It said that having considered all options it would not appeal the decision, which the British government said followed a "rigorous, fair and open competition".

The existing contract to make British passports is worth £400m and the new contract starts in October 2019, after Britain leaves the EU in March that year.

De La Rue's chief executive Martin Sutherland said he remained "surprised and disappointed", but he had taken a pragmatic business decision not to appeal. 

The company said its underlying operating profit for the year to the end of March would be in the low to mid £60sm range, it said. 

Revenue for the year had increased by about 6%, with growth across all product lines, it said, although it added that it was "cautious" about its current financial year. 

It said it would assist with the transition to the new supplier, and was expecting no impact on its performance in the next 18 months. 

Trade union Unite said the news that De La Rue was abandoning its appeal would come as a bitter blow to workers in Gateshead, who now faced an uncertain future.