Boris Johnson is facing separate Conservative rebellions on Brexit and Covid-19 rules, as Tory MPs mobilise to undermine the controversial legislation that overrides the EU withdrawal agreement. The tabling of an amendment by a former minister, Bob Neill, to the internal market bill in an effort to create a parliamentary veto on overriding the UK-EU divorce deal sets up a showdown next week on the bill’s second reading in the House of Commons. Momentum gathered pace on Friday as Neil’s initiative - which is backed by the former immigration minister Damian Green and the former minister and solicitor general Oliver Heald - was also signed by Simon Hoare, chair of the Northern Ireland affairs select committee. Among other senior Conservative figures who have also come out strongly against the bill’s proposed powers is the former party leader Michael Howard, who said he would be “very surprised” if the bill got through the the House of Lords, where the party did not have a majority. The peer said it was “a very sad day last week when the Northern Ireland secretary, Brandon Lewis, admitted that amending the UK’s Brexit deal with the EU will break international law”. “I never thought it was a thing I’d hear a British minister, far less a Conservative minister, say, which is that the government was going to invite parliament to act in breach of international law,” Howard told Sky News. “We have a reputation for probity, for upholding the rule of law, and it’s a reputation that is very precious and ought to be safeguarded, and I am afraid it was severely damaged by what was said on Tuesday and by the bill which is currently before parliament.” Howard’s intervention came after the former Conservative prime ministers John Major and Theresa May and former Conservative chancellor of the exchequer Norman Lamont also strongly criticised Johnson’s proposals. Amid signs of increasing unease among Tory MPs, there was support from a number of influential chairs of parliamentary committees for comments in the House of Lords by Howard. They included Tom Tugendhat, the chair of the foreign affairs committee, and Tobias Ellwood, the chair of the Commons defence select committee. Ellwood said on Twitter: “The rule of law is everything - if we forget this we forget who we are, what we stand for and the moral high ground that forms the foundation of our soft power.” Although Neill’s initiative would need backing from dozens of MPs in a parliamentary party that has tilted heavily towards a firm pro-Brexit position since the general election, Neill told Times Radio there was support for his amendment on the Tory backbenches. “I wouldn’t be pressing this issue if it was only a hobby horse of mine,” he said. The backlash within Conservative ranks on Brexit coincides with a separate rebellion on Covid-19 rules as one former minister claimed government plans would turn every public space “into the equivalent of going through airport security”. New regulations limiting gatherings in England to no more than six from Monday and moves to have Covid-19 marshals have sparked alarm among some Tory MPs who want parliament to have the power to review measures. Greater parliamentary scrutiny was needed, according to the Tory former minister Steve Baker, who said it was “now time to say that this is not a fit legal environment for the British people” and there should be a “voluntary system”. “And it is time for us to actually start living like a free people, not subjecting ourselves to constantly shifting legal requirements, which I think now no one can fully understand,” he told BBC Radio 4’s Today programme. “It seems to me the effect of having Covid marshals will be to turn every public space in Britain into the equivalent of going through airport security where we are badgered and directed … I’m not willing to live like this.” Challenged on why the Westminster government had not followed the path of devolved administrations in Scotland and Wales, which have exempted children under the age of 12 and 11 respectively from “rule of six” limitations on gatherings, the business minister, Nadhim Zahawi, said the move had been taken in England to provide “simplicity”. “It goes against the grain, the DNA of a Conservative government, to curtail people’s liberties, but the evidence suggests that the virus is at its most virulent in those social interactions, in the home, in the pub and outside, which is why we are reluctantly introducing the rule of six,” he told BBC Radio 4’s Today programme.