(Added information on Rio de Janeiro restrictions, the Sputnik V vaccine)

SAO PAULO, April 9 (Reuters) – Brazilian President Jair Bolsonaro on Friday denounced a Senate pending investigation into its handling of the record-breaking COVID-19 outbreak, which global health officials have compared to a “raging hell”.

Supreme Court Judge Luis Roberto Barroso ruled late Thursday that enough senators had signed up to the proposed investigation into the government’s pandemic response to launch an inquiry despite being stalled by the Senate leadership.

“This is a stitch between Barroso and the left in the Senate to weaken the government,” Bolsonaro told supporters outside his residence, accusing the judge of “politics.”

The Senate investigation represents the most severe political consequence to date for Bolsonaro’s approach to the coronavirus, which he compared to last year’s “mild flu” because he ignored health experts calling for masks and social distancing.

Bolsonaro has supported his criticism of the COVID-19 vaccine, but he has continued to attack governors who are trying to impose lockdowns and even lighter measures, accusing them of killing more with those restrictions than the virus itself.

COVID-19 has claimed more than 345,000 lives in Brazil, second only to the United States. One in four deaths from this week’s pandemic occurred in Brazil, where a brutal wave has swept through hospitals and recorded more than 4,000 deaths per day.

“What you have here is a raging epidemic,” said Bruce Aylward, senior adviser to the World Health Organization’s director general, in a public briefing.

But political exhaustion and pressure from Bolsonaro has prompted some governors to relax restrictions despite record deaths.

The state of Sao Paulo, whose governor was once a critic of the president, announced it was relaxing some restrictions next week even as its hospital struggled to handle the caseload.

Sao Paulo officials said the drop in hospitalizations had justified the decision to restart football matches without spectators, reopen shops selling building materials and resume take-out services at restaurants.

Meanwhile, the city of Rio de Janeiro, the country’s second largest city, let a series of restrictions imposed in late March expire on Friday. As a result, bars, restaurants and malls are now able to resume live services.

Brazil’s vaccination efforts, although faster than most countries in Latin America, have been slow compared to many developed countries and have so far relied heavily on one vaccine – Coronavac – developed by China Sinovac Biotech Ltd and has been frequently criticized by Bolsonaro.

On Friday afternoon, the national health agency Anvisa announced it was sending inspectors to two factories in Russia where the Sputnik V vaccine was produced to evaluate the safety of the jabs. (Reporting by Eduardo Simoes in Sao Paulo; Additional reporting by Tatiana Bautzer in Sao Paulo and Rodrigo Viga Gaier in Rio de Janeiro; Editing by Brad Haynes, Dan Grebler and David Gregorio)