Brexit has had a “significant adverse impact” on UK trade, according to the Budget watchdog’s assessment.

The Office for Budget Responsibility (OBR) said Brexit contributed to reducing trade volumes and business relationships between UK and EU firms.

Trade was also hit by slowing global economic growth, the OBR’s economic and fiscal outlook said.

“Near-term growth in exports and imports is lower than in our March forecast as slowing global GDP (gross domestic product) growth hits exports and a weaker outlook for consumption and investment weighs on imports,” the OBR said.

“Our trade forecast reflects our assumption that Brexit will result in the UK’s trade intensity being 15% lower in the long run than if the UK had remained in the EU.

“The latest evidence suggests that Brexit has had a significant adverse impact on UK trade, via reducing both overall trade volumes and the number of trading relationships between UK and EU firms.”

The OBR document also forecast payments of £18.9 billion to Brussels under the terms of the Brexit divorce deal between 2022-23 and 2027-28.