Vietnam's health ministry has detected a suspected new coronavirus variant which it said appears to be a hybrid of two highly transmissible strains.

“A new coronavirus variant with characteristics from the existing Indian and UK variants had been detected in Vietnam for the first time,” Vietnam's Minister of Health Nguyen Thanh Long told a national news conference Saturday.

The Southeast Asian country was held up as a leading example in containing the virus thanks to an aggressive strategy of early screening of passengers at airports and a strict quarantine and monitoring program.

But since late April, Vietnam has reported a sharp increase in Covid-19 cases. Almost half its 6,396 confirmed infections were reported in the past month alone, according to Johns Hopkins University data.

It is not clear if the suspected new variant is behind the sudden rise in infections. If it is, it could suggest it is more transmissible.

“The fourth wave of Covid-19 in Vietnam included infections in industrial zones, multiple sources of infections and the presence of various coronavirus variants. It will spread very fast and it will be very difficult to control,” the health minister said.

The World Health Organization said on Saturday its Virus Evolution Working Group was working with officials in Vietnam to confirm the possible new coronavirus variant after four people were confirmed to be infected with a suspected new strain.

“We have not yet made an assessment of the virus variant reported in Vietnam. We expect that more variants will continue to be detected as the virus circulates and evolves and as sequencing capacities are enhanced worldwide,” said WHO's technical lead for Covid-19 Maria Van Kerkhove in a statement.

“From what we understand, the variant they detected is the B.1.617.2 variant possibly with an additional mutation, however we will provide more information as soon as we receive it.”

The B.1.617.2 variant was first detected in India, where officials have said it and other variants have driven the country's spike in Covid-19 cases.

British health officials earlier this month upgraded B.1.617.2 to a variant of concern due to its rapid spread in the UK.