By Anastasia Teterevleva and Tom Balmforth

MOSCOW (Reuters) – Russia on Wednesday suspended the use of some Russian-made medical ventilators after two fatal hospital fires reported to involve the machines, a setback in its fight against the novel coronavirus.

The ventilators’ safety was called into question a day earlier after a fire at Saint George’s Hospital in St Petersburg in which five people died. That followed another fire at a hospital in Moscow which killed one person on Saturday.

In both cases, sources told the TASS news agency that the source of the fires had been faulty Aventa-M ventilators.

Authorities have procured hundreds of Aventa-Ms to help hospitals cope with coronavirus patients. Though Russia has so far suffered a low number of virus-related deaths compared to other countries, at 242,271 its infections tally is now the second highest in the world after the United States.

Russia sent a batch of the same ventilators to the United States in early April, though U.S. officials say the machines were not needed in the end.

Roszdravnadzor, the state healthcare regulator, said in a statement it was suspending the use in Russia of all such machines made after April 1.

It gave no explanation for the suspension, but noted that the ventilators had been used in the two hospitals where the recent fires had taken place which it said a day earlier it was looking into.

It was not immediately clear exactly how many new ventilators the suspension would cover.

Public procurement data cited by the Interfax news agency said that the Saint George Hospital in St Petersburg spent 441 million roubles ($6 million) last month on buying 237 Aventa-M ventilators.

The procurement contract was finalised on April 24, it said. Each ventilator cost 1.86 million roubles.

The ventilators are made at the Urals Instrument Engineering Plant (UPZ) in the region of Sverdlovsk.

Radio-Electronic Technologies Concern (KRET), which controls UPZ, said on Tuesday that its ventilators had passed all the necessary tests and had been used by medical facilities in Russia since 2012 without any safety concerns.

It urged people to avoid rushing to conclusions until the outcome of official investigations into the fires was known.

(Additional reporting by Maria Kiselyova; Editing by Andrew Osborn)