* Trade hampered by legal, price difficulties
* Firms subject to U.S jurisdiction remain wary
By Dmitry Zhdannikov
LONDON, March 10 (Reuters) - Royal Dutch Shell has bought only three cargoes of Iranian oil since sanctions were eased a year ago, a small fraction of what it used to buy and an indication of the legal difficulties and high prices that still hamper the trade.
The Anglo-Dutch firm did not give a reason for the drop in purchases, which were disclosed in its annual report, and the company declined to comment further.
But oil trading sources say Iranian oil is often too expensive and in any case remaining sanctions make dealing with the Islamic Republic a legal minefield.
As an example of sanctions-related difficulties, Shell's filings showed it had to disclose payments of only a few hundred dollars when its employees bought tickets with Iranian airlines.
After an accord was reached over Iran's nuclear programme, the European Union eased sanctions on Iran in January 2016 and the United States lifted some restrictions on dollar trade, moves that have allowed Iran to raise its oil exports sharply.
But while trade with Asian and European buyers soared, many oil majors subject to U.S. legal jurisdiction remain cautious about buying Iranian oil. Earlier this month the Trump administration imposed new sanctions after Iran tested a ballistic missile.
The price of falling foul of sanctions can be very high. In 2014 French bank BNP Paribas agreed to pay almost $9 billion to resolve accusations that it had violated U.S. sanctions including those against Iran.
Iran said last month that U.S. sanctions were making it impossible to cooperate with American firms on energy projects.
Of the oil majors, only Total has been buying Iranian crude over the past year in volumes comparable to pre-sanctions levels. France's biggest oil firm is looking to clinch a new deal with Tehran to develop oil and gas reserves.
Shell said in its annual report it had bought only three cargoes of Iranian oil over the past year.
These were a $45 million cargo in May, on which it made a profit of $1.1 million, followed by 2 cargoes in December costing $103 million and $106 million respectively. Those are still in transit so no profit or loss has been yet made on them, Shell said.
During the course of 2016, Shell also repaid $1.942 billion in debts to Iran for oil purchases it made before stricter EU sanctions were imposed on Iran in 2012.
At that times, Shell was buying as much as 200,000 barrels per day or six large cargoes of Iranian oil a month.
Despite some easing of U.S. restriction on trading with Iran in dollars, Shell said none of the payments was made in dollars.
But even with the difficulties, Shell said it had re-opened an office in Iran in 2016 and signed non-binding agreements with the National Iranian Oil Co to work together in the petrochemical sector, in oil and gas developments, and in gas export opportunities.
In a level of disclosure characteristic only of dealings with countries under U.S. sanctions, Shell also reported a series of tiny transactions with Tehran in 2016.
These included $224 in stamp duties, $168 paid to the Iranian consulate in the Netherlands to notarise documents, and $592 for tickets with Iranian airlines.
Shell, whose international dealings are usually reckoned in tens of millions of dollars, also disclosed a small fuel sale to the Iranian embassy in Argentina.
"This transaction generated gross revenue of $296 and an estimated net profit of $23," the report said. (Reporting by Dmitry Zhdannikov; Editing by Giles Elgood)