A spike in freight rates for tankers hauling oil has prompted a wave of vessels to join the lucrative trade, with dozens of ships switching their focus from hauling products to carrying crude across the world’s oceans.

A Marshall Islands-flagged oil tanker sailing from the United Arab Emirates to Singapore made a sudden course change and was heading toward Iranian territorial waters, British maritime security firm Ambrey said on Friday.

Revolutionary Guards were reported by maritime security to have intercepted the oil products tanker, Talara, taking it into Iranian waters.