Businesses in Swindon exported hundreds of millions of pounds' worth of goods to the EU last year.

Public spending watchdog the National Audit Office warns “widespread disruption” to UK trade with the European Union is likely when the country exits the single market on January 1.

HM Revenue and Customs figures show 646 businesses registered in the Swindon area exported goods to countries in the EU in 2019.

This outward trade was valued at £388 million – 44 per cent of the total value of exports included in the data.

The figures show 883 businesses imported goods from the bloc at a value of £1.05 billion last year – 63% of the value of all inbound trade.

The figures only include trade in goods, and not services.

In the UK, companies exported £168 billion worth of goods to the EU last year and imports £267 billion worth.

A report by the National Audit Office said there was “significant uncertainty” about whether preparations will be complete in time for the UK's departure from the single market.

It added the government could have avoided some of the problems if it had been swifter to tackle issues such as the number of customs agents to help traders.

Head of the NAO Gareth Davies said: “The January 1 deadline is unlike any previous EU exit deadline – significant changes at the border will take place and government must be ready.

“Disruption is likely and government will need to respond quickly to minimise the impact, a situation made all the more challenging by the Covid-19 pandemic.”

Talks between the UK and EU continue as negotiators try to finalise a trade deal before the end of the year. If they fail to do so, World Trade Organisation rules would kick in, which could increase the cost of imports and exports.

The talks continue as the House of Lords voted to remove controversial parts of the UK Internal Market Bill, which would allow the government to break international laws and override parts of its withdrawal agreement with the EU.

It would mean ministers could determine state aid rules in Northern Ireland and checks on goods moving between the nation and the rest of the UK.

US President-Elect Joe Biden is among those who say the proposed law could lead to a hard border between Northern Ireland and the Republic of Ireland, and has warned a US-UK trade deal is “contingent” on preventing this.

In the Swindon area, businesses exported goods to non-EU countries at a value of £486 million in 2019, while imports from outside the bloc were valued at £621 million.

A government spokesman said: “We are making significant preparations to prepare for the guaranteed changes at the end of the transition period – including investing £705 million to ensure the right border infrastructure, staffing and technology is in place, providing £84 million in grants to boost the customs intermediaries sector, and implementing border controls in stages so traders have sufficient time to prepare.

“With less than a month to go, it’s vital that businesses and citizens prepare too. We’re intensifying our engagement with businesses and running a major public information campaign so they know exactly what they need to do to grasp the new opportunities available as the transition period ends.”

He added that the government was working hard to implement the Northern Ireland Protocol – the part of the withdrawal agreement designed to prevent a hard border on the island of Ireland.