A tanker for Italy's IPLOM is sailing back home after loading 1 million barrels of Iranian crude, the Reuters news agency said.
Another vessel for Motor Oil Hellas loaded crude at Iran’s Kharg Island on April 20 and is about to deliver the first post-sanctions cargo to the Greek refiner soon, it added.
France's Total, Spain's Cepsa and Greece's Hellenic Petroleum became the first European companies to book Iranian crude for their refineries this year after the lifting of sanctions.
Others, including Italy's Saras and ENI, have expressed interest in buying.
"Buyers are gradually finding ways to handle the issues with shipping insurance and banking transactions, which in the end are hurdles rather than insurmountable barriers," Reuters quoted Richard Mallinson, an analyst with Energy Aspects, as saying.
"As more buyers join in we could see flows to Europe increase, which is certainly a goal for Iran," he added.
In Asia, Iran's key Indian client Essar Oil shipped in 204,500 barrels per day (bpd) of oil from Iran last month, a jump of 66.3% from February, Reuters said.
The private refiner bought no oil from Iran in March 2015 due to sanctions. With the lifting of sanctions, however, Iran's share in overall imports by Essar Oil in the last fiscal year rose to about 37% from about 28% a year earlier.
According to Reuters data, Indian refiners shipped in 14.4% more oil from Iran at about 251,100 bpd in the 2015/2016 fiscal year, which was the largest since the 2007/08 fiscal year.
Overall, India’s crude oil imports from Iran have topped 500,000 barrels per day (bpd), reaching the highest level in at least five years.
Indian refiners imported 506,100 bpd oil from Iran in March, a jump of about 135% from February.
Iran has said it will continue increasing its oil production and exports until it reaches the market position it held before the imposition of sanctions.
Iran’s exports shrank to about 1 million bpd after the West imposed new sanctions on the country in 2012.
Before the sanctions, Iran was the second-largest exporter in OPEC after Saudi Arabia, with exports averaging at about 2.3 million bpd.
The steady rise in exports points to the Islamic Republic’s success in regaining market share after the sanctions were lifted in January.