The mayor of London has accused the government of "putting dogma ahead of the national interest" by re-starting Brexit negotiations during the coronavirus pandemic.
Talks about securing a post-Brexit trade agreement between the UK and EU began on Monday, with negotiations expected to last around a week.
Sadiq Khan called for an extension to the 31 December deadline for Brexit trade talks between the UK and EU, in a letter to Michael Gove.
Mr Khan said that trade barriers and disruption caused by a no-deal Brexit would be “needless and hazardous”.
“The last thing the country needs as it tries to find a way back from the devastation wreaked by coronavirus is more chaos and uncertainty,” he wrote.
"Most Londoners will be deeply disappointed that at a time of crisis, the government is putting dogma ahead of the national interest.
“I urge the government to put political ideology aside and pursue the pragmatic route of seeking an extension to the negotiations so that we and our European partners can focus on recovery from Covid-19.”
A government spokesperson said: "We have taken unprecedented action to support businesses through this pandemic and to ensure the UK’s economic recovery is as strong and as swift as possible.
“An extension to the transition period would bind us into future EU legislation, without us having any say in designing it, but still having to foot the bill as we would still have to make payments into the EU budget."
The Cabinet Office said it will respond to Mr Khan's letter "in due course."