Thousands of people could fly from India to England before it is added to the travel “red list” from Friday, amid growing criticism that the government acted too slowly to restrict the spread of a variant which may be more resistant to vaccines. In a move announced hours after Boris Johnson bowed to pressure to cancel a key trip to India to boost economic ties, the health secretary, Matt Hancock, said most travel from the country would be banned from 4am on Friday. Only British citizens and residents will be allowed in, and all must quarantine in a hotel for 10 days. There are 16 direct flights from India to the UK scheduled to land before the deadline and many more indirect ones. Some 103 cases of the new variant first identified in India have been found “geographically dispersed” across the UK, according to Public Health England (PHE). Hancock said the “vast majority” had links to international travel. As India faces a deadly surge of the virus, recording more than 250,000 cases a day, UK scientists are working to see if the variant has any “concerning characteristics” such as being more transmissible or resistant to vaccines, Hancock said. Asked whether current jabs are effective against the variant, known as B1617, Hancock said: “We simply don’t know that … that is the core of my concern.” Nick Thomas-Symonds, the shadow home secretary, said it was “not good enough to try and shut the door after the horse has bolted, by adding countries onto a red list when it is too late”. Labour has called repeatedly for all travellers arriving in England to be subject to hotel quarantine. The shadow health secretary, Jonathan Ashworth, said B1617 was responsible for India experiencing “one of the world’s steepest surges right now”. He called for it to be classed as a “variant of concern” by PHE, rather than a “variant under investigation”, adding: “We already know this variant carries mutations of concern in other variants, and if we have learnt anything in the last 12 months, it is that this virus ruthlessly exploits ambiguities, that we must act fast when the situation is controllable because in a few weeks time it might not be.” Yvette Cooper, the chair of the home affairs select committee, said India should have been put on the red list when it was updated 10 days ago to include countries with “lower and slower Covid rates” including Pakistan and Bangladesh. She called for the government to publish the criteria behind countries being red-listed “so that we can see where the border gaps still are” and criticised ministers for “delays” in acting, in a week when Hong Kong “has identified 47 Covid cases just on a single Delhi flight”. The Tory MP Edward Leigh also urged Hancock to “resist those very powerful lobbyists” in the aviation industry and be “absolutely determined in following the evidence out there … in not allowing unnecessary travel and really be tough with this red list”. Hancock acknowledged that the “biggest risk” to Covid restrictions being eased in England was a “new variant that the vaccine does not work as well against”, and said surge testing would be rolled out “to make sure that we limit the spread as much as possible”. No data has yet been published revealing where in the UK the India variants have been discovered, but PHE said there was “no evidence of large clusters” in any particular area. Christina Pagel, a professor of operational research at UCL and a member of Independent Sage, said: “We are not likely to get definitive evidence on B1617 for a few weeks given low sequencing, testing and vaccination rates in India and low case numbers here.” Earlier, Downing Street announced that a trip Johnson was scheduled to take to India this month to meet India’s prime minister, Narendra Modi, had been cancelled, despite plans being changed last week to press ahead with a scaled-down version. On Sunday, Labour piled pressure on Johnson to “set an example” by pulling out. Reuters reported that the number of infections has passed 15m in India - the second highest in the world after the US – and that cases jumped by a record 273,810 in the last day. The UK Department for Transport also said: “The situation in India has deteriorated with an extremely rapid rise in cases,” adding that local infection rates have “almost doubled” in a week to 111 per 100,000 people – “higher than any other point”.