PARIS (Reuters) - France's aerospace industry has written to the European Commission calling for "proportionate and assertive" countermeasures if U.S. tariffs cause significant damage to the key export sector, a person familiar with the matter said.

The appeal from the country's powerful Gifas aerospace lobby, whose rotating presidency is held by Airbus, also calls for any retaliation to be fine-tuned so as to avoid hurting European companies that rely heavily on U.S. imports.

Gifas did not respond to a request for comment. The European Commission referred to an earlier statement by its president Ursula von der Leyen, who said the European Union was prepared to respond with countermeasures if talks with Washington failed.

President Donald Trump on Wednesday imposed sweeping tariffs on U.S. imports including 20% on EU goods and 10% on imports from Britain, home to engine maker Rolls-Royce.

The tone of the letter - juggling retaliation with softening the impact on French importers - reflects France's position at the centre of an interlocking supply chain for jets and engines.

France is home to the world's largest planemaker, Toulouse-based Airbus, which competes with U.S. rival Boeing ( BA ) for sales in the $150 billion global jet market and has core operations in France, Germany, Spain and non-EU Britain.

It also has a role at the heart of the world's largest engine maker by the number of units sold, CFM International, which is co-owned by Safran and GE Aerospace, supplies both Airbus and Boeing ( BA ), and has mainly stayed below the trade radar during a 50-year history.

Airbus is also a major customer of Pratt Whitney, the U.S. engine maker owned by RTX.

Aerospace is France's second-biggest exporter after the agri-food sector.

Analysts said U.S. airlines would face increased costs as a result of tariffs on Airbus jets delivered from Europe as well as a flow of parts feeding the supply chain for maintenance.

With Trump targeting metals and autos in the run-up to Wednesday's announcement, aerospace and airline executives had previously played down the prospect of direct tariffs on jets.