Former Health Minister Eduardo Pazuello denied on Wednesday that Brazil's far-right President Jair Bolsonaro had overturned his efforts to buy the COVID-19 vaccine made by China's Sinovac Biotech Ltd (SVA.O).

The vaccine has become the backbone of immunization efforts in Brazil as it fights the world's second-deadliest coronavirus outbreak, accounting for five out of every six shots given through April. But the government's use of the vaccine was long in doubt.

Last year, Bolsonaro disparaged the shot due to its "origins" and publicly clashed with Sao Paulo Governor Joao Doria, a political rival responsible for the partnership making finished doses of the Chinese vaccine at the Butantan medical center.

"The president never told me to undo any contract or agreement with Butantan," Pazuello, a three-star general in active duty, told a Senate commission investigating the handling of the pandemic in Brazil and the slow ramp up of the nation's inoculation campaign.

Senators reminded the general that he had announced plans to buy the Chinese vaccine in October, only to reverse himself after Bolsonaro dismissed the idea publicly the next day.

Asked about the dust-up at the time, Pazuello said in a video with Bolsonaro at his side: "One orders, the other obeys."

Ideologically motivated attacks on China by Bolsonaro and members of his inner circle have soured diplomatic relations despite the Asian nation's role as top trade partner.

Production of both the Sinovac vaccine and the AstraZeneca (AZN.L) shot, finished in Brazil with Chinese ingredients, has sputtered in recent months due to delayed shipments from China.

Pazuello resigned in March in the face of mounting criticism over the lack of vaccines. More than 435,000 Brazilians have died of COVID-19. Just one in eight Brazilian adults have been fully vaccinated.

The parliamentary inquiry is expected to damage Bolsonaro's political standing ahead of next year's elections by highlighting how he played down the virus and missed opportunities to ensure timely vaccine supplies.

After almost seven hours of testimony, the inquiry was suspended until Thursday morning.