Britain's plan for a temporary customs 'backstop' to solve the Irish border issue is 'not acceptable' and any fall-back option cannot be time-limited, the European Parliament's chief Brexit co-ordinator has told MPs.
Guy Verhofstadt said the Government's position that the backstop of continuing UK alignment with the EU customs union would cease by the end of 2021 if no other solution was found left him "puzzled".
Addressing MPs in London on Wednesday, the former Belgian prime minister said his understanding of a backstop was "a permanent system that is there that you don't use", saying the EU would seek a deal over the key Brexit sticking point.
He told MPs on the Exiting the European Union Committee: "I have never seen a backstop that is used for one year and then it disappears.
"No, a backstop is a fall-back position that you have in your pocket and you hope that you have never to use it. That is a backstop, in my opinion.
"That (the temporary backstop) was not in the proposal of the UK Government. I'm a little bit puzzled by the way the UK Government sees now that problem."
Mr Verhofstadt was speaking at the first of two grillings by MPs in Westminster on Wednesday.
He said he was looking forward to the Government's white paper, due to set out the position on leaving the EU.
He added: "I think that is it still possible to have for October/November an agreement on the political declaration. For that we need to speed up, certainly the negotiations in the coming months."
The former Belgian prime minister said the Brexit vote appeared to have resulted in a reduced appetite for withdrawal in other member states, while fuelling interest in EU reform.