One Vietnamese national was also nabbed in the bust, which police said took down "the largest gold smuggling ring ever dismantled" in the capital.

The Vietnamese have a long tradition of holding their wealth in gold, which trades at a premium in the communist country due to strict controls on how it can be bought and sold.

The smuggling ring, believed to be led by a Chinese national, was caught "red-handed" with five kilograms of raw gold in Hanoi, the police statement said.

According to police, the men had smuggled the gold from Hong Kong, "disguising it among shipments of electronic equipment to evade detection by authorities".

Before selling it, the ring used chemicals to cleanse the gold, melting and casting the precious metal into bars for clients in Hanoi and neighbouring Bac Ninh province.

The Vietnamese accomplice -- who accepted cryptocurrency in exchange for the gold and transferred it as instructed by the Chinese ringleader -- told police he received up to 200 million dong ($7,600) per month as payment.

Police said the ring had traded approximately 300 kilograms of gold worth more than $45 million between March and their arrest on an unspecified date.

Vietnam does not have a national gold exchange, and domestic banks do not offer individuals access to online trading platforms for precious metals.

However, people can buy gold at private and state-owned jewelry shops.