The British government Thursday denied it was planning to restrict travel in and out of London after the capital's rumour mill went into overdrive over the response to coronavirus.

"There are no plans to close down the transport network in London," Prime Minister Boris Johnson's spokesman told reporters. "And there is zero prospect of any restriction being placed on travelling in or out of London."

He condemned some of the recent reporting of the issue as "deeply unhelpful", saying it had "unnecessarily worried people" after rumours flew on social media.

London has been particularly badly hit by the outbreak of coronavirus, and speculation was rife in the capital on Wednesday that the government was planning to lock down the city. Scottish First Minister Nicola Sturgeon suggested tougher measures might be introduced in London because of the outbreak there, without giving any detail.

At his daily press conference on Wednesday, Johnson himself refused to rule anything out. The London transport authorities on Thursday closed dozens of Underground stations, but said they would maintain the system to enable "critical workers to make essential journeys".

Passenger numbers have dropped since Johnson on Monday advised Britons to work from home and avoid all non-essential travel or social contact to limit the spread of coronavirus. More than 100 people have died in Britain and more than 2,600 have been confirmed infected.

However, tests are being limited to those with the worst symptoms and public health officials have warned that as many as 55,000 people could have it.