The new lockdown could last longer than originally announced if the second coronavirus wave is not brought into control.
Michael Gove said the Government would be forced to extend restrictions if the R rate had not been reduced by December 2, The Mirror reports.
Speaking to Sky News’ Sophy Ridge on Sunday, the Cabinet Office minister also refused to rule out more lockdowns in the future.
Mr Gove said it was “likely” the shutdown would bring the R number below one – but the Government would react if it the four-week shutdown fails to do so.
He said: “We are going to review it on December 2 but we are always driven by what the data shows.
“We’ve got this four-week period during which we’re going to review progress. But of course we’ll always be driven by the data.
“It’s our hope, on the basis of the analysis we have, that we will have significantly reduced the reinfection rate.
He added: “If we chop away at all of the restrictions we may end up in a position where we don’t have a sufficiently strong team, bundle, raft of restrictions necessary in order to get R below one.”
Asked a fourth time if the national lockdown could be extended, he replied: “We’ll always take a decision in the national interest based on evidence. The best information we have.”
Asked a fifth time if it could be extended, Mr Gove replied: “Yes.”
Mr Gove also refused to rule out bringing in later national lockdowns after the second one is over.
He said: “One thing we can definitively say is unless we take action now the NHS is going to be overwhelmed in a way none of us could countenance. So therefore we have to take these steps.
“No-one in government relishes taking these steps. We believe that by doing this now we’ll be in a stronger position later in December to have a stronger testing regime, we’ve significantly increased testing capacity, and we also believe we’ll further have developed our approach towards therapeutics.
“But again, we’ll always be guided by the evidence on what is right, and what recent months have shown is this virus is a terrible force of nature.”
Labour leader Keir Starmer said on The Andrew Marr show that it was likely December 2 would be “a review date not an end date”.