Iran is preparing to shut down several transit routes through the Strait of Hormuz that it considers unauthorized, according to an adviser to the commander of the Islamic Revolutionary Guard Corps who spoke to the semi-official Fars news agency.

Mohammadreza Naqdi said the routes were established after sections of the strategic waterway’s rocky passages were blasted and damaged. He said the channels have been used by small vessels involved in oil smuggling.

The reported move comes as questions persist over the volume of oil and other commercial traffic passing through the Strait of Hormuz. The closure of the routes could further restrict maritime movement through one of the world’s most strategically important waterways.

Naqdi’s comments challenge claims that oil shipments through the Gulf and the Strait of Hormuz are returning to levels seen before the war, suggesting that some of the reported traffic may instead be connected to unauthorized or illicit routes.