TEHRAN (Reuters) - Iran ordered a halt to its oil sales to Britain and France on Sunday in a move seen as retaliation against tightening EU sanctions, as a team of U.N. inspectors flew to Tehran to press the Islamic Republic over its disputed nuclear program.

The European Union enraged Tehran last month when it decided to impose a boycott on its oil from July 1. Iran, the world's fifth-largest oil exporter, responded by threatening to close the Strait of Hormuz, the main Gulf oil shipping lane.

On Sunday, its oil ministry went a step further, announcing Iran has now stopped selling oil to France and Britain altogether - a powerful yet largely symbolic message since neither European nation relies on Iranian crude imports.

"Exporting crude to British and French companies has been stopped ... we will sell our oil to new customers," spokesman Alireza Nikzad was quoted as saying on the ministry website.