06:26

The British parliament will be confronted with a ‘take it or leave it’ choice on the Brexit divorce deal, if MPs vote after October 2018, according to a leading MEP.

Danuta Hübner, a Polish MEP, who chairs the European parliament’s constitutional affairs committee, argues it would be too late for British parliamentarians to have a meaningful say on the final treaty after October 2018 because formal negotiations would have already been completed.

EU negotiators have long said Brexit negotiations must be completed by October 2018 to allow time for the ratification of the treaty before the UK’s departure day on 29 March 2019. Asked if October 2018 was the final deadline to influence the agreement, Hübner told the Guardian:

Once it is finalised and it is signed by both parties, then any change to it means reopening negotiations, meaning we will not make it within the two years [the article 50 deadline], meaning there is a hard Brexit.

Stressing it was “purely a British decision” to decide how MPs will have a say on the withdrawal agreement, she said even the smallest change to the treaty would mean resuming negotiations.

Once anybody changes a comma or a dot or one-word, then there is no opinion, this has to go back to the negotiations.

The MEP was speaking before last night’s dramatic vote in the House of Commons, where MPs voted for parliament to have a meaningful vote on the Brexit deal.

The six-month window from October 2018-March 2019 is intended by the EU allow the treaty to be translated into the EU’s 24 official languages and scrutinised by committees in the European parliament, before the final plenary vote.

This view jars with the perception of some Tory rebels, such as Stephen Hammond, who told BBC Radio 4 on Thursday: “If [the Brexit deal] is concluded by October next year, that gives six months if things go wrong.”

The MP, who was sacked as a Tory vice chairman overnight, also pointed to the flexibility in the article 50 process, which could give the UK a few extra weeks beyond departure day. However, any extension would have to be approved unanimously by all 27 EU governments.

The European parliament will be asked to approve the article 50 treaty before March 2019, but will be unable to make any changes. Hübner, a member of the parliament’s Brexit steering group, said MEPs were seeking to exert influence in other ways.