The Iranian Navy has been seeking to increase its presence at sea amid a new escalation of tensions with the United States following the decision of the latter to withdraw from the Iran nuclear agreement, also known as the Joint Comprehensive Action Plan, and reimpose the economic sanctions in Tehran.
Washington sanctioned Venezuelan oil exports in January in an effort to oust President Nicolas Maduro and a massive power outage since last week halted crude exports from its primary port, essentially crippling the South American country's principal industry.
US sanctions against Iran were restored past year after Donald Trump announced unilateral withdrawal from the Joint Comprehensive Plan of Action (JCPOA), despite Iran complying with all conditions of the deal.
"Many big oil traders are very anxious about going into Iran due to Trump, and even the Chinese are trying to comply with what the Americans want", said Varzi, who is based in Britain.
USA has imposed sanctions on countries importing oil from Iran, while granting waivers to some countries, including India, until May.
In the first 11 months of this fiscal year that began in April, India's oil imports from Iran rose by 5.6 percent to 486,400 bpd as refiners boosted purchases ahead of the USA sanctions drawn by discounts offered by Tehran, the data showed.
The sources also added that the USA secretary of State would be seeking assistance from top oil executives to boost U.S. crude exports in to Asia and to back Trump Administration's policy of Iran quarantine over crude export agenda.
Around 70 per cent of Iran's revenue comes from its exports of oil and keeping its fleet running is essential.
South Korea A second Iranian official said talks with South Korea over the possibility of ordering as many as 10 supertankers, each able to carry up to 2 million barrels of oil, had been delayed by US sanctions.
It is not yet clear if reduced volumes of 8 million barrels a month is the new condition imposed by Washington for granting a second waiver to New Delhi from sanctions against Tehran. A third Iranian official said talks were still ongoing.
The administration is considering denying extension requests made by Italy, Greece and Taiwan - in part because they have not made full use of their waivers so far, one of the sources said.
"India, China and Turkey - the three tough cases - will continue to negotiate with the administration and are likely to keep their waivers", one of the sources said.
It is unclear whether the administration will be able to convince China, India and Turkey - all of whom depend heavily on Iranian oil and have criticized the USA sanctions on Iran - to reduce imports.
Washington is pressuring allies Japan and South Korea to reduce purchases of Iranian crude, the source said.
He said he expects China and India purchases alone to account for around 800,000 to 900,000 bpd.