Passengers flying into India's biggest airports on Wednesday complained of long waits and confusion as authorities sought to impose rules to try to stop the spread of a more transmissible variant of the coronavirus.

Like many countries, India has suspended flights from Britain, where cases have soared because of the variant.

People arriving from Britain before the ban came into force on Wednesday were being tested, including Kamini Saraswat whose plane landed in New Delhi just before midnight.

Despite pre-booking a test, her turn came nine hours after arrival and she told Reuters she was still stuck at the airport waiting for the result.

"There is no clear communication," said Saraswat, 28. "There is no social distancing."

Cellphone footage taken by Saraswat, shared with Reuters, showed long lines of passengers and crowds packed together around desks to get themselves tested.

Maharashtra has taken additional measures, quarantining most passengers arriving from Europe and the Middle East for a week.Many European and Middle Eastern countries have also suspended flights from Britain, but act as transit hubs for the big airlines flying into India.

Ishwari Gaurav Naik, who arrived in Mumbai from Dubai ataround 2 am on Wednesday, said she had to wait more than six hours before authorities sent her and three family members to aquarantine facility.

"There was huge chaos there," Naik said from her temporary accommodation at a school. "Nobody knows anything. There is no coordination between staff."

Delhi and Mumbai airport officials declined to comment, and local officials in both cities and health ministry did not respond to questions from Reuters.

The authorities have said that all required measures will be undertaken but have given few details of how the extra checks will be staffed.

India's plan to track down and screen all arrivals from Britain since November 25 is also getting stretched.

Immigration officials are tasked to provide the details of all travellers from Britain since then. They will be then contacted by state and district health officials.

A 54-year-old British citizen who flew into Mumbai on Monday morning said he was yet to receive either the result of his airport coronavirus test or any follow-up calls.

"The intention may be very good, but it is all down to the execution," he said, declining to be named.