BOSTON — An International Launch Services (ILS) Proton rocket carrying Mexico’s Centenario mobile communications satellite failed about eight minutes and 10 seconds after liftoff May 16 in what early reports said was a problem with the rocket’s third stage.

Russia’s Roscosmos space agency declined immediately to list possible causes, saying it would do so after more information becomes available.

Reston, Virginia-based ILS said in a statement that “preliminary flight information indicates that the anomaly occurred during the operation of the third stage, approximately 490 seconds after liftoff.” The launch, from the Baikonur Cosmodrome in Kazakhstan, occurred at 11:47 a.m. local time (1:47 a.m. EDT).

The 5,325-kilogram Centenario satellite, a 702HP geo-mobile spacecraft built by Boeing Space and Intelligence Systems, was insured for about $390 million, according to insurance officials.

As has been the case with previous Proton failures, the Russian government will create a commission to determine the cause of the failure, while ILS will establish its own Failure Review Oversight Board (FROB).

The failure continues what has been among the most worrying aspects of Proton’s recent record in the eyes of prospective commercial customers: There is no pattern to the anomalies. There have been issues clearly related to workmanship and quality control that have caused anomalies all over the rocket.

The issues have resulted in management overhauls at Khrunichev State Research and Production Space Center, Proton’s Moscow-based prime contractor. And while most of the failures have occurred during missions managed by Russia’s Federal launch program, not by ILS, the quality issues have put ILS on the sidelines of the global commercial launch market.

In the past two years, Europe-based Arianespace and SpaceX of Hawthorne, California, have divided the commercial market between them. Commercial fleet operators have steered clear of Proton since SpaceX’s Falcon 9 rocket has demonstrated an ability to lift 5,000-kilogram satellites into orbit.

But some operators, whose launch contracts were signed before SpaceX developed into a viable Arianespace alternative — the market wants at least two rockets to choose from — have stuck with ILS and with Proton.

Aside from the Mexican government — whose identical Morelos 3 satellite is scheduled for launch on a United Launch Alliance Atlas 5 rocket later this year — mobile satellite services provider Inmarsat of London will almost certainly be the hardest-hit by the latest failure.

Inmarsat’s Global Xpress Ka-band service needs three satellites to form an unbroken ring of coverage worldwide. Two are already in orbit, and Inmarsat recently told investors that the third would be launched in June, enabling GlobalXpress service to offer worldwide coverage later this year.

There is no Plan B for Inmarsat and the other ILS customers awaiting launch. Arianespace is full into 2017, and SpaceX’s launch manifest is also full for the rest of the year at least.

Breeze M refueling was completed yesterday and the Proton rocket rolled out to the pad today.

— ILS (@ILSLaunch) May 14, 2015

Peter B. de Selding was the Paris bureau chief for SpaceNews.