The post-Brexit transition period, due to conclude in December 2020, can currently be extended by mutual agreement for up to two years, the BBC reported.
But an amended Withdrawal Agreement Bill (WAB) - the legislation needed to ratify Brexit - the Commons is set to vote on this week would rule out any extension.
Downing Street has said that the government has planned to ask the new Parliament to have its first debate and vote on the withdrawal agreement on Friday.
With an overall majority in the Commons following the December 12 general election, Prime Minister Boris Johnson was expected to get the bill into law with few changes in time for the UK to end its European Union (EU) membership on January 31, 2020.
The government will then have until the end of the transition period on December 31, 2020 to negotiate a free trade agreement with Brussels before the trade relationship defaults to World Trade Organization (WTO) terms.
But critics have said the new clause would raise the chance of leaving the EU without a trade deal, reports the NNC.
But senior Cabinet Minister Michael Gove on Monday 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 WAB "in depth".
However, Shadow Brexit secretary Sir Keir Starmer said the move was "reckless and irresponsible" and he argued that PJohnson was "prepared to put people's jobs at risk".
( With inputs from IANS )