PARIS (Reuters) — France has banned flights in and out of the country by Iran’s Mahan Air, accusing it of transporting military equipment and personnel to Syria and other Middle East war zones, diplomats said on Monday, after heavy U.S. pressure on Paris to act.

The decision to revoke Mahan’s licence to operate in France was made after Germany banned the airline in January. “We knew of their activities from our own intelligence services and after the German move it was a question of credibility”, said a French diplomatic source.

Paris had considered revoking its licence more than two years ago under the presidency of Francois Hollande, but had backed down because it feared it could harm relations just after a nuclear deal between Iran and world powers was signed in 2015.

Mahan Air, established in 1992 as Iran’s first private airline, has the country’s largest fleet of aircraft and has flights to a number of European countries, including France, Italy, Spain and Greece.

The United States imposed sanctions on Mahan Air in 2011, saying it provided financial and other support to Iran’s Islamic Revolutionary Guards (IRGC), and Washington has been pressing its European allies to follow suit.

The French ban on the airline, which had four flights a week to Paris from Tehran, takes effect from April 1. The airline’s website is no longer taking reservations and calls to its offices in Paris were not answered.

Tensions between Paris and Tehran have grown in recent months as President Emmanuel Macron and his government have become increasingly frustrated with Iran’s ballistic missile tests, regional activities and a foiled attack on an Iranian exile group in France, which Paris says Iranian intelligence was behind.

Both countries only reappointed ambassadors to each other’s capitals last month after more than six months without envoys.

There are no plans at this stage to ban another airline — Iran Air — said one diplomat.