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The UK is resisting pressure to extend the Brexit transition period amid the coronavirus pandemic and has insisted trade negotiations are continuing “informally”.

MEPs have warned the UK faces a “double whammy” if Boris Johnson insists on quitting the EU’s single market at the end of a year likely to be heavily disrupted by coronavirus.

The centre-right European People’s Party (EPP), the largest group of MEPs in the European Parliament, stressed that extending the transition period beyond the end of the year was now “the only responsible thing to do” given the already tight timetable for agreeing a trade deal and the economic disruption of the pandemic.

But in response the prime minister’s official spokesman said: “The transition period ends on December 31 2020. 

“This is enshrined in UK law.”

The spokesman also claimed that no EU countries had asked the UK to extend the transition, and that negotiations were ongoing despite the cancellation of face-to-face talks earlier this month.

“We have shared legal texts and they are the subject of informal discussions between ourselves and the EU Commission,” the spokesman said.

“They are basically conversations which are taking place via telephone as both sides analyse each other’s respective legal texts.

“We would expect those sorts of conversations to be carrying on this week.” 

Asked if the negotiations were still on track, he said: “As we discussed at the beginning of those both sides know the deadline which we are working towards.

“The structure of the negotiations has changed to reflect the current situation with regard to coronavirus, so there are more continuous discussions taking place rather than the set rounds which were originally envisaged.”

European Commission spokesman Daniel Ferrie confirmed that talks between the EU and UK are “ongoing” and said both sides would provide clarifications on their proposals through “technical” exchanges between officials.

But the EPP said the coronavirus epidemic further complicated what many in Brussels already regarded as an unrealistically tight timetable for securing a deal.

MEP Christophe Hansen, a negotiator on the parliament’s international trade committee, said: “Under these extraordinary circumstances, I cannot see how the UK government would choose to expose itself to the double whammy of the coronavirus and the exit from the EU single market, which will inevitably add to the disruption, deal or no deal.

“I can only hope that common sense and substance will prevail over ideology. An extension of the transition period is the only responsible thing to do.”

The warning comes as the EU-UK joint committee set up to implement the withdrawal agreement was set to meet for the first time.

Because of the outbreak, the talks will take place by video conference, with the British side led by Cabinet Office minister Michael Gove and the EU by European Commission vice president Maros Sefcovic.

The EU’s chief negotiator Michel Barnier is reportedly continuing to recover after contracting the coronavirus earlier this month. 

German MEP David McAllister, who chairs the UK co-ordination group in the parliament, said now was the time for the UK to change tack over an extension to the transition.

“The coronavirus pandemic complicates the already very ambitious schedule,” he said.

“The EU has always been open to extending the transition period. The ball is now clearly in the British court.

“The United Kingdom would have to submit an official request. So far, the UK government has constantly rejected such an option.

“Under the current circumstances, London should carefully re-examine a prolongation.”