US tries to seize four Iranian tankers sailing towards Venezuela

US federal prosecutors are seeking to seize four tankers sailing towards Venezuela with gasoline supplied by Iran, the latest attempt to disrupt ever-closer trade ties between the two heavily-sanctioned anti-US allies.

The civil-forfeiture complaint filed late on Wednesday in the District of Columbia federal court alleges the sale was arranged by a businessman, Mahmoud Madanipour, with ties to Iran's Revolutionary Guard Corps, a US-designated foreign terrorist organisation.

"The profits from these activities support the IRGC's full range of nefarious activities, including the proliferation of weapons of mass destruction and their means of delivery, support for terrorism, and a variety of human rights abuses, at home and abroad," prosecutor Zia Faruqui alleges in the complaint.

The Associated Press news agency reached out for comment to the Iranian mission to the United Nations but did not receive an immediate response.

The Trump administration has been stepping up pressure on ship owners to abide by sanctions against US adversaries like Iran, Venezuela and North Korea.

In May, it issued an advisory urging the global maritime industry to be on the lookout for tactics to evade sanctions like dangerous ship-to-ship transfers and the turning off of mandatory tracking devices - both techniques used in recent oil deliveries to and from both Iran and Venezuela.

The campaign appears to be working.

On Thursday, the US Treasury Department lifted sanctions on eight vessels that were recently found to have transported Venezuelan crude.

The move followed an auction on Wednesday of 100,000 barrels of gasoline seized from a Greek-managed ship whose owner suspected the cargo was heading towards Venezuela.

As commercial traders shun Venezuela, President Nicolas Maduro's socialist government has been increasingly turning to Iran.

In May, Maduro celebrated the arrival of five Iranian tankers delivering badly needed fuel supplies to alleviate shortages that have led to days-long gas lines even in the capital, Caracas, which is normally spared such hardships.