Money concealed in pastries. REUTERS/Thomas Peter LONDON — A new IT system designed to cope with the five-fold increase in customs declarations expected after Brexit needs "urgent action" to be ready before the UK leaves the European Union in 2019, according to letters published by a parliamentary committee.

The status of the Customs Declarations Service – a revamped computerised duties and imports clearing system – was described as "in doubt" and with "major risks," Andrew Tyrie, the chairman of the Treasury Select Committee, said.

Around half of the UK's imports come from the EU and do not require checks because of Britain's membership of the customs union and single market.

Prime Minister Theresa May has signalled she will take the UK out of the 28-nation trading bloc as part of the Brexit process, which will see the number of declarations increase from 60 million a year to 300 million 2019, according to a report in the Financial Times.

If the CDS fails to become operational before that point, the consequences "could be serious," Tyrie said. "Much trade could be lost. The project, therefore, merits a high degree of scrutiny by Parliament."

"Customs is at the heart of the Brexit debate. It is part of the essential plumbing for international trade, and ensuring it continues to function smoothly post-Brexit has to be a priority for the Government," said Tyrie.

He said the status changed from "on time" to "in doubt" between November 2016 and January this year. "In just 67 days, confidence in the successful implementation of the Customs Declaration Service – a project that HMRC itself describes as 'business critical' – has collapsed," said Tyrie.

HM Revenue and Customs said in a statement to the FT: “We are fully focused on playing our part in making the UK’s exit from the EU, and our new trading relationship with the world, a success."

The CDS will be delivered by January 2019, the department said.