Amid broader delays to the Covid-19 vaccine's arrival in Brazil, Brazilian President Jair Bolsonaro has asked Prime Minister Narendra Modi to expedite a shipment of AstraZeneca's coronavirus vaccine, as per a letter on Friday.

The letter released by Bolsonaro's press office comes amid growing pressure to speed up Brazil's Covid-19 vaccine roll-out and end the world's second-deadliest pandemic.

"To enable the immediate implementation of our National Immunization Program, I would appreciate ... the supply to Brazil, with the possible urgency and without jeopardizing the Indian vaccination program, of 2 million doses," Bolsonaro said in the letter.

Meanwhile, critics say the immunisation campaign is running behind regional peers, and they question why the government has not moved more quickly.

Bolsonaro's message to PM Modi comes as the federally funded Fiocruz biomedical center said on Friday that the active ingredients needed to fill and finish millions of doses of AstraZeneca's coronavirus vaccine in Brazil, previously slated to arrive in the country on Saturday, may not land until the end of the month.

Fiocruz, which was counting on the shipment Saturday to supply the government with doses this month, said it was in talks to import more finished doses of the vaccine, likely from India on top of the 2 million it has already ordered.

A source involved told news agency Reuters the active ingredient is ready to be shipped to Brazil but is waiting for an export license from China, where it is produced.

Earlier, Fiocruz requested an emergency use authorization for AstraZeneca vaccines coming from India, which are expected to arrive in Brazil in the middle of this month.

On Friday, Brazil reported 52,035 new confirmed cases of the novel coronavirus in the past 24 hours, and 962 deaths, the health ministry said.

The South American country has now registered 8,013,708 cases since the pandemic began, while the official death toll has risen to 201,460, according to ministry data, in the world's third-worst outbreak outside the United States and India.