The UK government has added London to a coronavirus watchlist as the number of infections steadily rise in the country, news agency PTI reported. The government also imposed stringent restrictions in several other cities. The announcement came after the R number, or the rate at which the infection is spreading, went further up beyond the mark of one.

The R number indicates the average number of people each person with coronavirus goes on to infect. An R number below 1.0 signifies that the pandemic is under control. In the UK, that number is now between 1.2 and 1.5, which means that on average every 10 people infected will infect between 12 and 15 others.

London Councils, which represents the bulk of the boroughs in the UK capital, said that while no additional measures are being deployed for the UK capital yet, testing capacity is being boosted.

“London is at a very worrying tipping point right now,” said London Mayor Sadiq Khan.

“It’s vital that testing capacity is increased immediately in London and focused in the areas it is needed most. Any delay will mean letting the city down and will cost lives,” he said.

Other than London, the regions that will be put under stricter lockdown restrictions are Cardiff, Swansea and the town of Llanelli in Wales.

The lockdowns for Cardiff and Swansea mean that around 50% of the Welsh population will be subject to local lockdowns by the end of the weekend.

Households in Leeds are also set for a ban on people meeting in private homes or gardens, bringing it in line with rules in Bradford, Kirklees and Calderdale and several other areas in northern England.