Four Vietnamese men believed to be part of an international drug ring were arrested in a raid that netted 183 pounds of heroin allegedly smuggled into Boston from Hong Kong in a bean sprout washing machine, authorities said.

The men were arrested Wednesday in two separate raids, one of which occurred as three of the suspects tried to sell part of the washing machine to a scrap metal dealer, authorities said.The heroin, most of which was removed from the machine by federal agents before the raids were carried out, was estimated to be worth hundreds of millions of dollars and perhaps as much as $1 billion, authorities said.