A senior German MEP has sided with Theresa May in the Brexit talks, by accusing the EU negotiators of attempting to “punish” Britain.

Hans-Olaf Henkel accused Michel Barnier, the chief negotiator, of planning to impose a bad exit agreement on Britain as a warning to other countries tempted to leave the EU.

Guy Verhofstadt, the European Parliament's Brexit negotiator, was also guilty of wanting “to make a mess out of this whole unhappy situation”.

“I have the impression, by their public statements, that indeed they would like to set an example,” said Mr Henkel, the deputy head of the European Parliament's industry, research and energy committee.”

“They want to punish Britain and make sure that non-one else is leaving the European Union.

“By the very fact that they say that a country which leaves the European Union should not have the same deal as a country which is in the European Union you can demonstrate what they mean.”

Mr Henkel, the president of the Federation of German Industries and a former chief executive of IBM, urged other MEPs – who enjoy a potential veto of any Brexit deal – “not to listen” to their own negotiators.

His outburst will strengthen the hand of the Prime Minister who has repeatedly accused the EU of seeking to “punish’ Britain – and even of a “plot” to stop Brexit.

The criticism came as the second round of the talks appeared to have run into trouble within 24 hours of resuming in Brussels, over the vexed issue of the so-called “divorce bill”

EU diplomats have hit out at Britain’s failure to agree it must pay a hefty financial settlement for Brexit, suggesting the controversy will “stall” the talks.

Eyebrows were raised after David Davis, the Brexit Secretary, left the talks after just one hour on Monday, leaving the negotiations to his officials.

The agenda for the four-day talks includes the rights of EU citizens in the UK – and British ex-pats in the EU – and the Northern Ireland border, as well as the exit bill.

Last week, Mr Barnier urged the British side to present detailed proposals on all three priorities before the talks resumed, but there is no evidence that this happened.

Instead, the UK is expected wait to several weeks before formally setting out its position on the bill, using this week's talk to interrogate and challenge the EU's stance.

Mr Henkel is a member of a Eurosceptic grouping in the Parliament and his views on the EU’s approach to the talks are not thought to be shared by most European politicians.

Nevertheless, the German MEP called Brexit “disastrous”, pointing to the controversy over Britain’s withdrawal from the Euratom nuclear regulator.

He said the UK received funding for world’s largest nuclear fusion experiment, at the Culham Centre for Fusion Energy in Oxfordshire, which is of “fundamental importance for the world”.

“I see that the whole project may collapse if this funding doesn’t work anymore,” Mr Henkel warned.