German Europe Minister Michael Roth urged Britain on Monday to think about reviewing its decision to leave the European Union.

"The door to the EU always remains open - perhaps think about it again," Roth told German broadcaster ARD. Asked if that meant holding a second referendum, he replied: "Exactly."

After seeing her deal to leave the EU resoundingly defeated in parliament last week, British Prime Minister Theresa May has opened talks with lawmakers from all parties to try to find a way to move forward with Brexit.

"I have often said Shakespeare could not have written any better the tragedy we are now witnessing in Britain," Roth said. "I am not so sure now, because Shakespeare would have pushed up against the limits of his imagination," Roth said.

"I expect firstly that the Britons say now what they want. They have in the past weeks told us what they don't want. Now we need a clear signal. We are ready for negotiations," he added.

Separately, Economy Minister Peter Altmaier told RBB radio he was optimistic a so-called hard - or no-deal - Brexit could be avoided.