A Chinese firm has stopped verifying safety and environmental standards for Iran [1]ian ships, becoming the last top certification provider to end marine work there as the trade noose on Tehran tightens.

The China [2] Classification Society (CCS) is the last of the world's top 13 such companies, all members of the International Association of Classification Societies (IACS), to confirm it has ended Iran-related certification work, key to insurance and ports access for ships.

Earlier this month Hong Kong said it would stop allowing 19 ships linked to Iran's biggest cargo carrier the Islamic Republic of Iran Shipping Lines from operating under its flag.