Boris Johnson has been warned that his coronavirus restrictions could be “challenged in law” unless MPs are granted the right to vote on them in advance.

Parliament’s top backbenchers said the current system whereby the government can make new regulations without prior approval is “not widely acceptable” and may be “challenged in court”.

The pressure from the Commons liaison committee, made up of all select committee chairs, came as the prime minister attempted to strike a deal with dozens of Tory rebels who are threatening to defeat him over the issue tomorrow.

The MPs are lining up behind an amendment from Sir Graham Brady, powerful chair of the backbench Tory 1922 committee, which would give them the right to veto new Covid-19 rules.

There is increasing anger on the Tory backbenches at the government passing new regulations “by decree”, and the PM’s confusion over his own local lockdown rules for the north-east of England is likely to have added to the distress.

Brady’s amendment is thought unlikely to be selected for debate on Wednesday.

But he was in talks with Commons leader Jacob Rees-Mogg on Tuesday night, with the government hoping a compromise can be thrashed out to avoid explosive scenes on Wednesday.

One of the rebels told HuffPost UK that shortening the time before MPs can approve or strike down regulations in retrospect from 21 days to five days is one idea that has been discussed.

But many of the disgruntled backbenchers are unlikely to be happy unless they can get a veto in advance.

Reports also suggest that MPs could be given the right to vote on regulations in advance except in emergencies when the government needs to act very quickly to control the spread of coronavirus.

In a letter to Johnson, liaison committee chair Sir Bernard Jenkin said: “Various proposals are being made that would require the approval by a vote of the House of Commons before or immediately after new restrictions come into force.

“The majority of us support this principle and expect that the government will also wish to accept it. 

“The idea that such restrictions can be applied without express parliamentary approval, except in dire emergency, is not widely acceptable and indeed may be challenged in law. 

“We trust the government will accept a suitable amendment or agree a motion to that effect, at the earliest possible opportunity at or before the debate on Wednesday.”

A Whitehall source said of talks with rebels: “There was a very constructive meeting yesterday. Everyone recognises the need to balance the ability of government to act swiftly with the need for proper parliamentary scrutiny. There is a dialogue ongoing.”