The illegal Vietnamese entrants were detained Sunday night and sent for quarantine near the border with Thailand, Vietnamese Ambassador to Cambodia Vu Quang Minh said on his official Facebook page Monday.

The Vietnamese Consulate General in Cambodia's Battambang Province is cooperating with Cambodian and Vietnamese authorities to handle this "very dangerous illegal entry."

Minh said Cambodian authorities provided the passports of those arrested for verification. Vietnamese counterparts have requested Cambodia to carry out all prescribed procedures, including Covid-19 testing and strict isolation.

Some Vietnamese working in Thailand are trying to illegally enter Cambodia to return to Vietnam, which is a major threat to both Vietnam and Cambodia, he said.

Thailand is struggling with a new Covid-19 outbreak linked to migrant workers at a seafood market in Samut Sakhon, a province near Bangkok. Over 1,300 new cases have been recorded in the country over the past 10 days, prompting the Cambodian government to tighten border restrictions.

A group of six Vietnamese had previously traveled from Myanmar to Thailand by truck on Dec. 15 before leaving for Cambodia on Dec. 23. They illegally entered Vietnam through a border gate in An Giang Province on Dec. 24 before traveling to other localities.

Four of them, found in HCMC and the Mekong Delta, have tested positive for the novel coronavirus and two others showed negative results.

Prime Minister Nguyen Xuan Phuc has called on people to report anyone they find illegally entering the country, warning they are potential sources of Covid-19 infection.

Vietnam's Covid-19 tally stands at 1,451, with 35 deaths. No local transmission has occurred for more than a month, but health authorities are apprehensive that the recent illegal entrants could spark a new wave of community transmission.