Turkish security forces have seized $1 billion of counterfeit money in Istanbul, and arrested six people involved in the operation, including one Ghanian and three Swedish nationals, the governor's office said on Friday.

Gendarmerie forces tracked the suspects to a storage space in Istanbul's Kagithane district, where they seized the fake $100 bills meant to be sent to African countries, the office said.

The suspects' homes were searched and their cash and jewellery confiscated. The Swedish and Ghanaian consulates were notified.

The counterfeit haul was the largest in Turkey's history, the governor's office said.