Sao Paulo, Brazil's largest city, has stepped up efforts to clear old graves to make way for an increase in COVID-19 deaths.

Gravediggers in white hazmat suits worked in Vila Nova Cachoeirinha cemetery in the city's north on Thursday, opening tombs of people buried years ago and bagging decomposed remains for removal to another venue.

Relocating remains is common practice in cemetery activities, according to the municipal secretary in charge of funeral services.

However, with Brazil experiencing its worst coronavirus wave since the pandemic started over a year ago, it has taken on new urgency.

On Thursday, Brazil's health ministry recorded 3769 new COVID-19 deaths, just missing a daily record for the third day in a row.

Bolivia declared on Thursday that it would close its borders with Brazil due to concerns about a new strain of the disease discovered in the larger country.

A day earlier, the Brazilian biomedical institute Butantan announced the discovery of a new version that resembled one first discovered in South Africa and appears to be more vaccine-resistant.

The South African version, as well as an earlier variant found in Brazil, is more infectious.

Chile also closed its doors to all foreigners on Thursday, imposing a strict curfew, as the nation passed one million cases since the outbreak started.

According to Jose Miguel Bernucci, secretary of Chile's National Medical Association, "what is happening in Brazil is a global danger."

“Closing the borders won't benefit us as much with the existing models as it will with the new variants that can be produced in the future.”

As cases rise and Brazilian President Jair Bolsonaro refuses to support masks and lockdowns, countries across the region are concerned that Brazil is becoming a breeding ground for new variants.

After the United States, Brazil's outbreak is the second-deadliest in the world, with around 3100 deaths and 74,000 new cases every day over the past week.

To meet demand, Sao Paulo has resorted to late-night burials, with cemeteries allowed to remain open until 10 p.m.

Staff in masks and full protective gear have been digging rows of graves in the Vila Formosa cemetery under floodlights and a full moon.

On Tuesday, the city of Sao Paulo reported 419 burials, the most since the pandemic started.

If the rate of burials continues at this rate, city officials say they would need to take further precautions.