KARACHI, Pakistan 

Afghanistan on Wednesday returned 21 tankers of what it said was substandard oil imported from Iran.

In a statement, the Afghanistan National Standards Authority (ANSA), the country's audit watchdog, said the tankers, which were transporting substandard oil, have been returned to Iran through the port of the Farah province.

Emphasizing its active efforts to prevent imports of substandard fuel into the country, the authority urged traders to import quality materials or face legal consequences.

This is the second oil shipment returned to neighboring Iran in less than three months.

In late August, Afghanistan returned 45 tankers of substandard oil imported from Iran.​​​​​​​