A total of 11 out of about 2,200 passengers who returned to Mumbai from the United Kingdom since November 25 have been found coronavirus positive, the civic body officials said on Monday.

Of these 11 passengers, five passengers had arrived last week, while the six others had returned before December 22, Dr Managala Gomare, executive health officer, Brihanmumbai Municipal Corporation (BMC), told PTI.

Another official said samples of these 11 passengers have been sent to the National Institute of Virology (NIV) in Pune for genome sequencing to find if they are infected with a new strain of the coronavirus.

"Currently, 187 of the 590 passengers who returned from the UK last week are placed under institutional quarantine at various hotels," Dr Gomare said.

She said the state government had handed over to the civic body two lists of more than 2,000 passengers, who arrived from England between November 25 and December 22.

She said all of them are not yet contacted.

"Our teams are trying to trace all of them. Meanwhile, six of them who reached Mumbai before December 22 have been found positive for coronavirus," said Dr Gomare.

In view of the emergence of a new coronavirus variant in the UK, the Mumbai civic body on Sunday issued revised guidelines to ensure the compulsory quarantine for 14 days for all passengers arriving from the UK, Europe, and the Middle East.

As per the amended Standard Operating Procedures (SOP), travellers will be kept under institutional quarantine after arrival and RT-PCR test will be conducted on the seventh day from the arrival at the respective hotels, institutional facilities at their own coast.

"If the report of the test is found negative, the passenger would be discharged from the institutional quarantine after seven days with the advice of seven days mandatory home quarantine. A total of 14 days quarantine is to be ensured," the Brihanmumbai Municipal Corporation (BMC) had said.

As per the guidelines, home quarantine stamp will be put and undertaking will be taken from the travellers that they will abide to be in home quarantine.

If the test result is found positive, the passenger will be shifted to designated Covid-19 hospital like Seven Hills for UK and GT hospital for travellers from other countries for further evaluation and treatment, the civic body said.