THE hated Brexit backstop is ILLEGAL under EU rules, top lawyers have warned today.

Brexiteers described the latest analysis of the Northern Irish backstop as "devastating" - as Theresa May fights with Brussels to get it ripped up.

MPs threw out her Brexit deal last month mainly over fears Britain would be tied to the bloc forever after we've left.

In a briefing from Herbert Smith Freehills lawyers concluded that "the backstop in its present form is illegal as a matter of EU law".

They argued that it broke EU laws because it wasn't consistent with promises to "promote peace" as it defied the Good Friday Agreement with Northern Ireland.

And it concludes that the backstop "has no end date" and could last forever - exactly what Brexiteers fear.

The experts say that if the backstop were given a time limit, or the ability for one side to pull out of it, then it could work and be consistent with other EU treaties.

The EU should accept and change if to get it through the Commons, it hints, or put all of it in the arrangements for Britain's future with the bloc.

Owen Paterson MP said this evening: "Devastating briefing."

Today's dire warning comes as Mrs May considers how best to persuade Brussels to change their mind and edit the agreement.

She told businesses and leaders in Northern Ireland yesterday that she would ensure that any deal did not risk peace there.

But the EU insisted today that they would not re-open the deal in any way.

Donald Tusk risked fury by saying there was a "special place in hell" reserved for Brexiteers who wanted to leave without a plan.