Russia on Saturday said it had ordered a full check of engines used on its key Proton rocket after a cargo ship crashed last month due to engine disintegration and an inspection revealed factory violations.

A plant making engines for both the Soyuz and Proton rockets had workers "switch technology and documentation," Deputy Prime Minister Dmitry Rogozin said, vowing to punish those responsible.

Earlier reports said engine parts used on the second and third stages of the widely-used Proton rocket had been swapped for cheaper variants.

"A necessary check of engines with possible technical defects will be made," Roscosmos space agency said, adding that the launch schedule will be "coordinated" with the verifications.

Rogozin said launches using the Proton rocket would resume in three and a half months.

He did not mention the Soyuz rockets, which are used for manned flights, particularly the next ISS mission set for late March.

The Progress freighter crashed in Siberia after it failed to reach orbit in early December due to a malfunction during third-stage separation.

A commission appointed to investigate the matter concluded earlier this month that the malfunction was caused by the breakup of the third-stage engine, either due to "foreign materials" getting inside or an "assembly fault".

The cargo ship was carried by the Soyuz rocket, but the same engine is used on the Proton rocket, according to its maker, Voronezh.

A report by Kommersant daily said that all engines built for the third and second stages of the Proton rocket had been recalled, while a test showed that a key heat-resistant part made of material containing precious metals had been switched during assembly.

It was not immediately clear whether Soyuz rocket engines would also be checked or recalled.

The chief of the Voronezh plant quit earlier this month "for reasons of unsatisfactory work and product quality."

The launch in December of the EchoStar-21 communications satellite by a Proton has already been delayed.

Russia is currently the only country executing manned space flights to the ISS.

Its space industry had suffered a string of setbacks and launch failures in recent years, while corruption scandals have plagued its new space port in the Far East.