Dinh Xuan Hien, 30, and Dinh Cong Quan, 31, are under investigation for "brokering illegal entry to Vietnam," Da Nang police said Monday. Their detainment was announced after both had completed mandatory 14-day Covid-19 quarantine, officials added.

If prosecuted, the culprits could be jailed for up to 15 years.

In December last year, four Chinese admitted to having been smuggled by a person named Lao Cui from China to Vietnam, en route to Cambodia.

On Dec. 26, the four traveled to Hanoi where a car containing Hiep and Quan collected them. The group was passing through Da Nang's Lien Chieu District on Dec. 27 when stopped by traffic police.

A subsequent check revealed the Chinese had no eligible visa to enter Vietnam. Hien confessed he had been hired to transport the migrants to HCMC for VND20 million ($866). All occupants were later taken into quarantine.

Vietnamese border guards detained around 31,460 people trying to illegally enter the country last year as the government stepped up efforts to combat Covid-19.

Around 25,000 were entering from China and the rest from Laos and Cambodia, defense officials said at a meeting last Friday.