A Melbourne fruit market owner has been fined a record $660,000 for exploiting a newly arrived refugee by underpaying him by $25,000 in just four months of work.

Abdulrahman Taleb, former operator of Sunshine Fruit Market, was found to have paid the Afghan refugee as little as $3.50 an hour.

"For some of the time Mr Kazemi was simply not paid at all," Judge Philip Burchardt said in his judgment, describing the underpayment as "enormous" and "egregious".

Syed Jamal Udin Kazemi, understood to be in his 20s, was initially unpaid and later received a flat rate of $10 an hour up to $120 a day for his work at the market, the court found.