Millions of people over 50 could be told to stay at home to prevent another full nationwide lockdown, it is claimed.
Ministers anxious about a coronavirus second wave are reportedly considering giving people aged between 50 and 70 a personalised risk rating advising them whether to shield.
It would mean that people could be be forced to shield because of their age in coming months - and vulnerable people identified in March would once again be made to isolate themselves.
It is being weighed up as one of a string of alternatives to reimposing full nationwide lockdown restrictions, as happened in March, it is claimed.
Tory minister Robert Jenrick today insisted the idea was not being "actively considered" and said it was "speculation". No10 sources also called the reports "speculative".
But Mr Jenrick also refused to rule it out in future, saying: "You would expect the government to be considering all of the range of options that might be available to us."
Yesterday restrictions which told 2.2million vulnerable people to remain at home - 'shield' -during the spring peak of Covid-19 were lifted in England, Scotland and Northern Ireland. Wales will follow later in August.
People who were shielding can now no longer receive government-paid food parcels or Statutory Sick Pay.
The end of shielding went ahead in spite of Boris Johnson putting the brakes on further easing of lockdown rules, as new data suggests the number of new Covid-19 cases in England is rising again.
Previous shielding guidance was not based on people's age. The 2.2million people were instead picked based on their medical condition.
However, according to the Sunday Times and the Sunday Telegraph, an option has been raised to focus more on age in future.
Under the proposals, a greater number of people would be asked to shield, based on their age or particular risk factors that have been identified since March, the Sunday Telegraph says.
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It could even see those aged between 50 and 70 given "personalised risk ratings", said the Sunday Times - a move that would add to the 2.2 million who were deemed most vulnerable and previously told to remain at home.
The Sunday Times reported the Conservative Party leader held a "war game" session with Chancellor Rishi Sunak on Wednesday to run through possible options for averting another nationwide lockdown that could stall any potential economic recovery.
Tory minister Robert Jenrick appeared to play down the possibility of age-related restrictions, but did not rule them out completely.
He told Times Radio today: “This is just speculation. You would expect the government to be considering all of the range of options that might be available to us.
“That’s not something that’s being actively considered.
"We have a shielding programme, we’ve provided very clear guidance to those people who we’ve identified as being extremely clinically vulnerable and we’ve supported them and we'll continue to support them, for example with the delivery of medicines if they require it.
"And if necessary in localised areas, for example in Leicester, we've extended the period in which we're asking people to shield which meet those characteristics."
People in Luton and Blackburn with Darwen have been told shielding should continue to August 17.
In Leicester shielding also continues until at least August 17 and could run in some parts of the city beyond that.
Likewise shielding remains in place until August 16 in Wales.
But people in Greater Manchester and parts of Lancashire and West Yorkshire have been told shielding is over - despite new restrictions there banning two households from meeting indoors.
Bowling alleys were set to reopen this weekend, but on Friday Boris Johnson deferred this, saying it was not save to reopen further businesses.