South Korea has consolidated its position as the largest investor in post-sanctions Iran with the latest agreement worth $1.9bn.

South Korea’s SK Engineering & Construction has signed a heads of agreement with the Tabriz Oil Refining subsidiary of Iranian state refiner NIORDC and state construction firm NIOECC for a €1.6bn ($1.89bn) upgrade of the 110,000 b/d capacity Tabriz oil refinery.

The agreement follows SK’s June 2016 signing of an MoU with NIORDC for a...