The United States has tightened its anti-Iranian campaign after warning Tuvalu this week to stop reflagging Iranian oil tankers.
Washington, which is Israel's and Saudi Arabia's ally, is opposed to Iran having nuclear power plants.
The US has imposed sanctions in a bid to cripple the economy of Iran which is the world's third largest oil exporter while Tehran has been shunning the US dollar for its oil trade with mainly China.
The US Treasury official, David Cohen, says these new sanctions will make it much harder for Iran to deceive potential purchasers about the origin of the oil
"We are also identifying the ships owned by the National Iranian Tanker Corporation or NITC including their IMO numbers, their specific immutable identification numbers. This will assist oil importers around the world to know if they are dealing with an Iranian tanker even if NITC repaints, renames and reflags its ships in an effort to deceive."
The US Treasury official, David Cohen.