Boris Johnson has failed to clarify the detail of tighter coronavirus restrictions coming into force in north-east England from midnight.
When asked, he said residents should follow guidance from local authorities and wrongly suggested the rule of six did not apply outside.
Mixing between households in pub gardens and outdoor restaurants spaces will be against advice.
Critics say a lack of detail has led to confusion.
Labour deputy leader Angela Rayner said the PM was “grossly incompetent” for not knowing the rules, saying: “These new restrictions are due to come into force across huge parts of the country tonight. The government needs to get a grip.”
Earlier, education minister Gillian Keegan was also unable to clarify the new rules.
Speaking on BBC Radio 4’s Today programme, she said: “I don’t know the answer to that question.”
In areas not covered by extra restrictions, the rule of six – meaning social gatherings are limited to six people – applies in private homes, indoors and outdoors, and places such as pubs, restaurants, cafes and public outdoor spaces.