Tories attempt to hijack powerful decision-making committee to ram through new post-Brexit laws

The Conservatives are demanding to pack a crucial decision-making committee with their own MPs, despite losing their Commons majority at the election, The Independent can reveal.

Now Opposition parties plan to join forces to derail the attempted fix, in what threatens to be the first autumn Parliamentary clash over leaving the EU. At stake is the extent of the Prime Minister's power, through the Repeal Bill, to force through up to 1,000 "corrections" to EU law without MPs necessarily voting on them.

The vast number of statutory instruments (SIs) to be passed – some under "Henry VIII" powers – has already provoked accusations of a Government power grab. The alarm has been raised over the protection of rights for British workers and consumers, lower environmental standards and curbs on the devolution of powers across the UK.

For example, Ms May has vowed workers' rights will be protected, but has declined to say whether that will be enshrined in law – and has made no promise at all about food standards. One source involved in the battle over the make-up of the committee said: "If the Tories go ahead with this, there will be a dust-up in September, because we will bring it to a vote in the Commons." The controversy comes as the Prime Minister returns from her summer holiday attempting to stamp her authority on a Cabinet "on manoeuvres" over Brexit policy in her absence. Chancellor Philip Hammond and Liam Fox, the International Trade Secretary, wrote a joint article, insisting Britain would not seek to remain in the EU "by the back door", in an attempted show of unity.

However, the pair remain split over the extent of a transitional deal which much of the Cabinet is seeking, for up to three years from withdrawal day in 2019. Meanwhile, Anna Soubry became the first Conservative MP to threaten to quit the party if Ms May fails to "confront the ideologues" and continues to push for a hard Brexit. The Commons row centres on the obscure Committee of Selection, which has the crucial task of arranging which SIs will be pushed through Parliament and when. In the last Parliament, the Conservatives claimed five of the nine MPs on the committee, but officials have advised they are entitled to four only, after their Commons majority was destroyed.

Nevertheless, when talks broke up in acrimony as the summer recess began, the Tories were still insisting on five MPs – and the power to defeat the other parties.

The source added: "The Tories are trying to pretend the election didn't happen and that they still have a majority – and, therefore, should have the majority on this committee.