Shadow Brexit Secretary Sir Keir Starmer said there was "chaos at the heart of Government" over the approach to leaving the European Union.
The flagship Brexit legislation - the European Union (Withdrawal) Bill - had been widely expected to return to the Commons next week.
The Department for Exiting the European Union (Dexeu) insisted that no date had formally been set for the legislation's next stage.
But Sir Keir said: "This is further proof that the Government's Brexit strategy is in paralysis.
"The negotiations are in deadlock and now a crucial piece of legislation is facing further delay.
"There is chaos at the heart of Government. Theresa May cannot unite her Cabinet or her party behind this deeply flawed Bill.
"There are now serious questions about whether the Prime Minister can deliver Brexit."
Commons Leader Andrea Leadsom will confirm next week's business in the regular statement on Thursday.
Mrs Leadsom told MPs last Thursday that there had been "300 amendments and 54 new clauses" proposed for the so-called repeal bill, which will put existing EU regulations on the domestic statute book.
She said it was "taking a bit of time to have proper, thoughtful, well-considered responses" to those, but the Bill would return "just as soon as we're able to".
That had been taken as a sign the Bill could return in next week's business.
MPs are due to spend eight days debating the repeal bill at committee stage, which will then undergo further scrutiny in the Commons and the Lords before it is approved.