Iran has stopped selling crude oil to British and French companies, the Oil Ministry announced Sunday.
"Oil sales to British and French companies have ceased," spokesman Ali Reza Nikzad Rahbar said in a statement on the ministry's official Web site.
"We have taken steps to deliver our oil to other countries in the place of British and French companies," he added.
The decision is not expected to have a big impact on either Britain or France, however.
France bought only 3 percent of its oil - 58,000 barrels a day - from the Islamic republic last year, and Britain is believed to be no longer importing Iranian oil. The move, however, is being seen as a warning shot to other EU nations that are larger consumers of Iranian oil, such as Italy, Spain and Greece.
Sunday's announcement did not name those countries, but they are included in a EU-ratified decision to stop buying Iranian oil that was announced last month and which will take full effect from July.
The International Energy Agency revealed that Italy sourced 13 percent of its oil (185,000 barrels per day), from Iran, while Spain imported 12 percent of its oil needs (161,000 bpd) and Greece bought 30 percent of its needs (103,000 bpd).
Iran, OPEC's biggest exporter after Saudi Arabia, pumps 3.5 million bpd, of which it exports 2.5 million barrels.
Seventy percent of the exports go to Asian countries, China and India especially. More than 20 percent, or around 600,000 barrels per day, go to the European Union.
However, the European Commission said that even if Iran did cut its sales to the European Union, it would make little difference as EU buyers were already switching suppliers, to Saudi Arabia in particular.