Work has stopped at Brazil's Arena da Amazonia World Cup stadium after Saturday's death of two workers in separate incidents.

Judge Maria Nely Bezerra de Oliveira ruled construction be halted at the venue pending a report guaranteeing workers' safety.

Marcleudo de Melo Ferreira, 22, died early Saturday after falling 35m from the stadium's roof.

In an unrelated incident, Jose Nascimento, 49, died of a heart attack at another part of the stadium's complex.

According to family members, Nascimento had been suffering stress, having worked seven days a week to meet construction deadlines.

Oliveira said the death was similar to that of another worker at the venue, who fell 5m from scaffolding in March.

She said health and safety inspectors had reported 114 infractions since work at the stadium began.

"Because of the risks inherent with this type of development, we have constantly monitored the work," Oliveira said.

"But despite the relentless work of the authorities, we have nevertheless witnessed the repeated noncompliance with work laws. Now with the death of yet another worker, we believe it is time to take action to prevent further tragedy."

Construction firm Andrade Gutierrez will be fined 40,000 US dollars for every day it does not comply with the ruling.

The company said it had begun investigating the cause of the fatalities.

Work is being conducted around the clock at six World Cup stadiums as local organizers scramble to be ready for the June 12-July 13 tournament.

Football's governing body FIFA earlier this month admitted at least three stadiums would miss the original December 31 construction deadline.

Saturday incidents bring to six the number of worker deaths at Brazil's World Cup stadiums.

Earlier this month two were killed when a crane collapsed at Sao Paulo's Itaquerao stadium.

In March a worker died after falling from a 5m structure, also at Arena da Amazonia.

And in June last year a 21-year-old man fell 30m to his death at the Estadio Nacional in Brazil's capital Brasilia.

Arena da Amazonia will host four World Cup matches, including the Group D clash between England and Italy on June 14.