The US Environmental Protection Agency (EPA) is targeting an 80% cut in nitrogen oxide (NOx) emissions from large vessels, including oil tankers and container ships, that burn heavy and polluting bunker fuel.

After 2012, ships heading to the US will face higher costs for bunker fuels. From 2016 engines will need to be modified to cut emissions, requiring the purchase of retrofit kits.

In December, the organisation said that new marine-diesel engines installed on US-flagged and registered ships from 2011 must meet a lower NOx standard.

The EPA estimates that operational and hardware costs to the shipping industry to meet engine and clean-fuel requirements could reach $1.85bn by 2020.

The US plans to create an Emission Control Area that requires ships entering a zone of up to 200 nautical miles off the US coast to burn fuel with a maximum sulphur content of 1%.