London Mayor Sadiq Khan has urged in a letter the UK government to ask all secondary schools and colleges in the capital to shut early ahead of Christmas.

Khan said he also wanted schools to reopen later in January amid "significant" COVID-19 outbreaks among 10- to 19-year-olds.

Khan told the government it should consider moving London from Tier 2 to Tier 3 of restriction levels, putting the city on "very high alert." This would also allow authorities to introduce more restrictions.