Dutch police have found three-quarters of a ton of heroin stashed in a raisin-filled container from Iran, one of their biggest hauls yet, public prosecutors said on Monday.

The container carrying 764 kilos (1,680 pounds) of heroin valued at around 17 million euros ($23 million) was spotted by customs officials in the Rotterdam port a week ago, prosecutors said in a statement.

Police followed the container to the small village of Hagestein, around 60 kilometres (37 miles) east of Rotterdam, and swooped on Thursday, arresting two men aged 69 and 33 "as they were unloading the cargo of raisins".

The unnamed 69-year-old appeared on drug smuggling charges in a Rotterdam court on Monday. He was remanded in custody for two weeks, prosecution spokesman Wim de Bruin told AFP.

The 33-year-old has been released pending an investigation.

"This is certainly one of the biggest hauls seized so far," De Bruin said.