Stena Line has warned that a no-deal Brexit could hit food supplies to the UK.

The firm is the largest ferry firm on the Irish seas, with three UK ports. The group has said that “anxiety is high” on ports.

Ian Hampton, the senior executive of Stena Line, told BBC Radio 4’s Today Programme: “We can’t plan on the basis of what we don’t know, so we’re very anxious about the outcome.”

The friction following a no-deal Brexit was likely to have an impact on trade flows, which could mean traders bypass the UK altogether.

Hampton also expressed concern whether a new computer system to handle customs declarations could handle the increase in volumes following a no-deal Brexit.

“I’m not sure it can. This is a system that was not written for the purpose we’re now asking of it and I think that would [create] huge concerns.”

An EU spokesperson has said it was engaging with ports throughout the Brexit transition.

“It is crucial to keep trade flowing when we leave the EU,” the spokesman said.

“That is why we are proposing a pragmatic and ambitious future economic relationship with the EU, and we remain committed to reaching agreement on the Withdrawal Agreement and future framework this autumn.”

On Thursday, Theresa May said that there was a possibility of increasing the Brexit transition period.

“It was mentioned – both sides mentioned the idea of an extension of a transition period as one possibility that is on the table and would be looked into,” said the European Parliament President Antonio Tajani.

“Theresa May during her speech said it’s possible to achieve an agreement also on a transition period, but not with a clear position on the timing,” he added.

In further news, a source has said that there will be no special Brexit summit in November due to sufficient progress already being made.