Sri Lanka's Civil Aviation Authority said on Monday that though international airports would reopen on Tuesday, travelers from Vietnam would not be allowed in until further notice, Xinhua news agency reported.

This decision was taken due to the spread of hybrid versions of Covid-19 in Vietnam, it said, quoting State Minister of Aviation and Export Zones Development D. V. Chanaka.

The minister said the ban would also apply to people transiting through Vietnamese airports and visiting the country in the last 14 days.

Bahraini authorities prohibited arrivals from Vietnam from June 1.

The U.K. government said it is monitoring a suspected Covid variant detected in Vietnam ahead of a decision on travel restrictions due later this week that could result in more destinations being added to its red list, which requires arrivals to go into hotel quarantine, The Guardian reported.

Vietnam is currently on the amber list, which requires self-isolation at home upon return, but is among the countries that could be upgraded to stricter quarantine measures.

Vietnamese Minister of Health Nguyen Thanh Long said on Saturday a hybrid variant with characteristics from the Indian and U.K. coronavirus strains and which spreads rapidly through the air has been found.

Vietnam's containment of Covid was a worldwide success story until last month when incidence began to shoot up.

Since late April it has been struggling with a fourth wave of Covid, its most challenging so far, with 4,549 cases reported in 37 of its 63 cities and provinces.

Tan Son Nhat and Noi Bai, the country's largest airports, have temporarily banned foreign arrivals.