PARIS (Reuters) - French jet engine maker Safran posted an 18.1% year-on-year increase in first-quarter revenue and reaffirmed financial targets for the year, while joining its U.S. partner GE Aerospace in lowering a target for engine deliveries.

The Paris-based company posted quarterly revenues of 6.22 billion euros ($6.67 billion), up by 19.1% on an underlying basis.

The widely watched civil aftermarket business grew 27.3% in dollar terms. But deliveries of the LEAP jet engine were flat after a slow start to the year in plane production, notably at Boeing ( BA ).

Safran co-produces engines for Boeing ( BA ) and Airbus narrow-body jets with GE Aerospace through their CFM joint venture, which is the sole supplier to Boeing's ( BA ) 737 MAX family of jets and competes with Pratt & Whitney on the Airbus A320neo series.

Echoing GE earlier this week, Safran is now projecting LEAP engine deliveries will be up by 10%-15% this year, a downward revision from its previous estimate of 20%-25% growth.

Earlier this month, Reuters first reported that Boeing's ( BA ) MAX output had plunged into single figures per month.

Overall propulsion revenues, up 15.4% on a like-for-like basis, lagged other divisions including aircraft interiors whose 23.8% growth was driven mainly by service revenues that are linked to rises in air traffic.

However, business-class seat deliveries fell 25%.

($1 = 0.9328 euros)