The EU imposed tough sanctions against Iran last month, which included a freeze of the country's central bank assets and an oil embargo set to begin in July.
Iran's Oil Minister Rostam Qassemi had warned earlier this month that Tehran could cut off oil exports to "hostile" European nations. The 27-nation EU accounts for about 18 percent of Iran's oil exports.
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"Crude oil exports to British and French companies have been halted," Oil Ministry spokesman Ali Reza Nikzad-Rahbar said on the ministry's shana.ir website. "We have our own customers and have no problem to sell and export our crude oil to new customers."
Targeting Britain and France appeared to be a political decision by Iran to punish the two countries for supporting tougher sanctions against Iran over its disputed nuclear program.
Britain's Foreign Office declined comment, and there was no immediate response from French officials.
Sunday's announcement follows a flurry of contradictory signals by Iran about backlash against the EU for imposing a boycott on Iranian oil.
Last week, state media said Iran was planning to cut off oil exports to six EU nations, including France, but later reports said the nations were only told that Iran has no problem finding replacement customers for the European shipments.
The EU sanctions, imposed last month, were part of Western efforts to target Iran's critical oil sector in attempts to rein in Tehran's nuclear program.
The West fears Iran's nuclear program aim to develop atomic weapons. Iran denies the allegations, and says the program is for peaceful purposes like producing electricity and medical isotopes.
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