Personnel at a border station in Quang Ninh, which is home to the popular Ha Long Bay and shares a border with China, caught the two Vietnamese men bringing the three Chinese on two motorbikes on Monday night, border guards said.

At around 10 p.m. they were on a patrol when they spotted the men and asked them to pull over.

One obeyed but the other tried to flee, forcing the guards to chase after them. All were arrested.

The two Vietnamese, Pham Van Uoc, 35, and Le Van Thong, 26, are Quang Ninh locals, while Liao Qian Hong, 37, and Lin Jia Tian, 33, are from Xi'an, the capital of Shaanxi Province, and Hoang Hua, 38, is from Fujian Province.

They said they had entered Vietnam to gamble at the casinos at the Lilai International Hotel and Hong Van Hotel in Quang Ninh's Mong Cai Town.

They had first hired a Chinese man to help cross the Beilun River in Guangxi Zhuang Autonomous Region and into Quang Ninh Province for 5,000 yuan ($700) each. There they met Uoc and Thong.

Uoc said he had been contacted by a Chinese man from Dongxing, a city in Guangxi, by telephone, and asked to help take his three friends into Vietnam.

He then asked Thong, his cousin, to bring a motorbike for the task.

All five have been put in quarantine at a facility in Mong Cai for 14 days, as per Covid-19 prevention protocols.

On June 10 border guards in Mong Cai had also arrested three Chinese men entering illegally overland. They were planning to take a bus to the central town of Nha Trang to gamble there.