The Iranian oil ministry announced on Sunday it has stopped all sales of crude oil to British and French companies.
A spokesman was quoted on the ministry’s website as saying:
"Exporting crude to British and French companies has been stopped … we will sell our oil to new customers. We have our own customers … The replacements for these companies have been considered by Iran."
The announcement came after threats earlier this week to stop oil supplies to other countries in Europe.
Tehran is thought to attempt to pre-empt sanctions by the EU, stopping all imports of oil from the country from 1 July.
Iran is facing increasing pressure and sanctions due to its continued enrichment of uranium, which the US and the EU believe to be an attempt to build nuclear warheads.
Iran relies on crude sales for 80% of its exports revenue.
Iran denies State TV reports of ending EU exports - 15 Feb 2012
Iran threatens EU with sanctions - 29 Jan 2012