The Brexit withdrawal agreement must either be accepted or rejected by MPs and should not automatically be subjected to amendments, according to a letter and a memorandum released by the government.

Some MPs pushing for another vote on Britain’s membership of the EU were hoping to add an amendment. Brexiters also planned to use the opportunity to push for a Canada-style trade deal.

Dominic Raab, the Brexit secretary, sent a letter to fellow MPs on 10 October implying that the government wanted to restrict the parliamentary process.

“Once the deal is presented to parliament, the procedure through which it is voted upon must allow for an unequivocal decision, and one which is clear to the British public,” he wrote to the Commons’ procedure committee.

A six-page memorandum published by the government on Wednesday appears to restrict the opportunity of laying down amendments on the agreement. It says that the motion will be amendable, but appears to be enforcing a “take it or leave it” vote on the final withdrawal deal.

One Whitehall source said the memo meant that amendments would only be accepted if the main motion passed first. If the motion fell, the amendments might only constitute “points of view”.

Responding to Raab’s letter, shadow Brexit secretary Keir Starmer said: “Labour doesn’t accept that the choice facing parliament will be between whatever deal Theresa May cobbles together or no deal. That is not a meaningful vote and ministers can’t be allowed to silence parliament. MPs must be given the opportunity to scrutinise, consider and, where appropriate, amend any resolution the government puts forward. She clearly doesn’t think she can win a straight vote in parliament without fixing the rules.”

Amendments to the motion would not automatically alter the text of the withdrawal agreement or delay the timing of the UK’s exit from the EU, the memo said. It warns: “Amendments – even those which may not intend to affect approval – may actually result in the government being unable to ratify the withdrawal agreement. It is important, however, to recognise the need ultimately for the house to consider the question that is in reality before the UK – whether or not to accept the deal that the government has negotiated with the EU.”

The memo also demonstrates why John Bercow’s role will be crucial to the final deal. It says that according to house procedures, “selection of amendments is in the hands of the Speaker … more than one amendment can be selected by the Speaker”.

A government spokesperson said Raab’s letter to the procedure committee set out the different ways in which you could take amendments during the vote on the final deal.

“It also sets out the issues that could arise if the vote does not lead to a clear outcome that provides legal certainty,” she said. “We look forward to hearing their views.”