Boris Johnson has insisted it was "essential" he travelled more than 100 miles during lockdown to promote new mass vaccination centres.
The prime minister was asked why he and his team made the surprise trip to Bristol while his government was telling the public to stay at home to reduce the spread of coronavirus.
He replied: "I have come because it's part of my job, and the guidance also says that you should go to work and do your job normally if you absolutely have to.
“I think it is essential that I explain to the public what we are doing to roll out the mass vaccination centres.”
He adde: “Everybody should be asking themselves whether they need to be leaving home, whether they need to be doing something that could actually end up spreading the disease."
The vaccination centre at Bristol’s Ashton Gate was one of seven sites opened on Monday. The other six are at Epsom racecourse in Surrey, ExCel London, Newcastle's Centre for Life, the Manchester Tennis and Football Centre, Robertson House in Stevenage and Birmingham's Millennium Point. The London centre, at the site of the capital’s Nightingale Hospital, less than eight miles from the prime minister’s home.
Mr Johnson was also been criticised after he was spotted cycling seven miles from Downing Street in the Olympic Park in Stratford, east London, on Sunday afternoon, despite government guidance stating "you should not travel outside your local area".
It comes Mr Johnson warned tougher measures may be needed amid reports that the government is considering tightening the current lockdown.
But he said it would be “far, far better for people to obey the rules that we have”.
Speaking at the launch of the mass vaccination centres, the PM vowed the government could meet its target of vaccinating the top four priority groups - including the over-70s, care home residents, frontline health workers and the clinically extremely vulnerable - by mid-February.
He said: "We're going to throw absolutely everything at it to get it done. Today, I think I can confirm that we've done roughly 40 per cent of the 80-year-olds in this country already. We've done about 23 per cent of the elderly residents of care homes."
Two million people in the UK have been vaccinated so far, he added.
During his trip to Ashton Gate on Monday, the prime minister met 90-year-old Marion Fursman, who served for three years in the Women's Royal Naval Service the Second World War.
Ms Fursman said she was "absolutely delighted" to receive her first dose of the vaccine and told reporters she believed the government was dealing with coronavirus "excellently".
