Six out of eight critical IT systems required to allow the UK’s borders to function under a no-deal Brexit are in danger of not being ready, Whitehall’s spending watchdog has found.

The National Audit Office has also concluded that with 31 days to go before the UK is due to leave the EU, the readiness of UK’s businesses are a “red-rated” risk if the government crashes out of Europe.

The findings were released on Wednesday evening in a memo sent to the public accounts committee.

Meg Hillier, the chair of the committee, said serious questions remained about whether the UK would be prepared at the border, and what this would mean for individuals and businesses.

“It is alarming that six of the eight critical IT systems needed are in danger of not being ready in time and that government assesses readiness of traders as one of its most significant risks,” she said.

The report examined eight systems at the border across departments including HM Revenue and Customs, Defra, the Food Standards Agency and the Department for International Trade.

One IT project, the Automatic Licence Verification System – which was meant to allow the importation of regulated horticultural, plants, live animals and animal products – had deteriorated since last September, the report found.

The Import of Products, Animals, Food and Feed System, developed to control the importation of animals and high-risk food and feed from the EU, still had the same risk profile as six months ago, auditors said.

Auditors noted that this month civil servants rated the risk to trader readiness as “red-rated”.

“A survey of external readiness commissioned by government in December 2018 found that 31% of businesses cited lack of knowledge as a barrier preventing preparedness, and that 50% of small businesses were yet to take action to prepare for no deal,” the report said.

A government spokesperson said the report showed “real progress” had been made at the UK’s borders. “We have also taken steps to minimise disruption through phasing in certain checks required at the border and continuing to apply the risk-based approach to customs checks we use today,” he said.

“The necessary resources we need to keep the border secure will be in place, including an additional 900 Border Force officers by March 2019, and we’ve been communicating extensively with businesses about the steps they need to take to prepare.”