The post-Brexit transition period – due to conclude in December 2020 – can currently be extended by mutual agreement for up to two years.
But an amended Withdrawal Agreement Bill the Commons is set to vote on this week would rule out any extension.
Critics say this raises the chance of leaving the EU without a trade deal.
But senior Cabinet Minister Michael Gove insisted both the UK and the EU had “committed themselves to making sure that we have a deal” by the end of 2020.
He also promised Parliament would be able to scrutinise the Withdrawal Agreement Bill “in depth”.
Shadow Brexit secretary Sir Keir Starmer said the move was “reckless and irresponsible” and he argued that Prime Minister Boris Johnson was “prepared to put people’s jobs at risk”.
Liberal Democrat interim leader Sir Ed Davey said: “The only way Johnson can meet the December 2020 timetable is by giving up all his previous promises to Leave voters and agreeing to all the demands of the EU.”
Downing Street has said the government plans to ask the new Parliament to have its first debate and vote on the withdrawal agreement – the legislation needed to ratify Brexit – on Friday.
With a majority of 80 following Thursday’s general election, Mr Johnson is expected to get the bill into law with few changes in time for the UK to end its EU membership on 31 January.
The government will then have until the end of the transition period on 31 December to negotiate a free trade agreement with Brussels before the trade relationship defaults to World Trade Organization (WTO) terms.
Senior EU figures, including the bloc’s chief negotiator Michel Barnier, are sceptical that a deal can be agreed within that time.
As well as ruling out an extension, the Independent reports that the amended withdrawal agreement may omit previous “provisions to ensure that workers’ rights were not weakened after Brexit”.
Mr Gove said workers’ rights would be “safeguarded” in separate legislation adding that the government wanted to make sure the Withdrawal Agreement Bill passes through Parliament “cleanly and clearly”.
But shadow chancellor John McDonnell said the government would “sacrifice our basic rights and certainty for business at the altar of turning the UK into a Trump-supporting tax haven”.
And Labour’s Barry Gardiner said his party would be less likely to support the bill if clauses on workers’ rights and the environment were removed.
Source: BBC UK