European diplomats say the European Union has reached a preliminary agreement on imposing sanctions on Iranian oil.

Reuters reports that the details and timing of the sanctions have not yet been determined.

The report indicates that European governments reached an agreement toward the end of December, and even countries such as Greece, which were previously opposed to sanctions on Iranian oil, are now on board with the plan.

A French Foreign Ministry spokesman announced on Tuesday that there has been “good progress” in EU talks on the speedy implementation of sanctions.

The European Union and the U.S. started a new wave of sanctions against Iran, after the International Atomic Energy Agency released a report last November, indicating that Iran may be developing weapons as part of its nuclear program.

Spokesmen for the Iranian oil industry have said Iran can easily replace its European customers.

Talk of sanctions against Iranian oil prompted the Iranian administration to warn that it would block the Strait of Hormuz, the strategic waterway for a large portion of Persian Gulf oil, if those sanctions went ahead.

The U.S. navy responded that it will not allow Iran to interrupt business in the Persian Gulf.

Iran provides 18 percent of EU oil demands, with Italy and Spain being the major customers. China, Japan, India and South Korea are the other major destinations for Iranian oil exports.