Bankers had begun returning to the office in recent weeks after a lockdown that began in March in response to the coronavirus pandemic.

The government has said people should work from home wherever possible from Thursday, the day it reported the highest number of daily COVID-19 cases so far.

The FCA republished its criteria for banks and other financial firms on who can be designated an "essential worker" and work from the office.

"It remains important for financial services firms to continue to identify and monitor key workers to ensure that firms respond effectively in the event of further local or national lockdowns," it said.

The FCA said key workers should have a letter signed by a senior company official stating they have been designated an essential worker in line with the criteria set out by the watchdog.

The government has said that reimposed pandemic restrictions could last up to six months.

Earlier on Thursday, the FCA said banks and investment firms need more "creative solutions" to avoid misconduct by staff set to work from home for longer than expected due to the pandemic's second wave.

(Reporting by Huw Jones; Editing by Kirsten Donovan)