FILE PHOTO: Conservative MP Jacob Rees-Mogg attends a meeting of the pro-Brexit European Research Group in London, Britain, November 20, 2018. REUTERS/Henry Nicholls

LONDON (Reuters) - Any assurances Britain secures from the European Union on the Irish backstop in the Brexit divorce deal will be “completely irrelevant” if they are not in the Withdrawal Agreement, eurosceptic lawmaker Jacob Rees-Mogg said on Monday.

He said the chance of Britain leaving the EU without a deal had increased after Prime Minister Theresa May delayed a vote in parliament on the agreement and said she would instead go back to the EU to seek further reassurances.

“Anything that is not physically in the treaty is ‘junior law’, so if the prime minister comes back with a statement, warm words, it’s completely irrelevant because the treaty outranks it,” Rees-Mogg told reporters. “Unless it’s an amendment to the treaty, it’s pointless.”

The strongest opposition to May’s deal centers around the so-called backstop, an insurance policy designed to prevent a hard border between EU member Ireland and British-ruled Northern Ireland.

Rees-Mogg echoed the Northern Irish Democratic Unionist Party (DUP), which is supposed to prop up May’s government but is committed to voting against her deal, by saying the backstop had to be removed entirely.

“It would be transformative if the backstop were removed. But, this is the whole backstop, this isn’t some paragraph saying it will finish in 2025 or something. It has to be out, because no one would believe the 2025 date,” he said.