BRASILIA: The medical emergency the Yanomami people of Brazil are suffering can only be overcome if illegal gold miners that invaded their reservation are evicted, an indigenous health official said on Tuesday.

"The malnutrition crisis continues to be extremely serious. We believe the reopening of medical units can only be done when the miners are all removed," Indigenous Health Secretary Ricardo Weibe Tapeba told a news conference.

About 20,000 wildcat miners on the Yanomami reservation in the state of Roraima in northern Brazil have brought malaria and severe food shortages that caused the death of starving Yanomami children, he said.

Some 700 patients have been airlifted to the state capital of Boa Vista and are being treated at the CASAI indigenous health center hospital and a field hospital set up there, Weibe added.

A second field hospital was urgently needed in the village of Surucucu inside the reservation, he said, as well as the improvement of the runway there to allow better air transport for food, medicine and health personnel.

Armed violence brought by criminal gangs supporting the miners led to closing of the health centers in the reservation, Brazil's largest, where some 28,000 Yanomami live in an area of savannah and Amazon rainforest the size of Portugal.

Severe malnutrition spread in Yanomami villages, where game for hunting became scarce and water from the rivers was polluted by the mercury used by the miners.

President Luiz Inacio Lula da Silva declared a medical emergency for the Yanomamis, and his recently installed government is planning to expel the miners with a task force involving the military, police and agencies that protect the environment and Brazil's indigenous peoples.

Later on Tuesday, Lula said on Twitter that his government would not allow illegal mining on indigenous lands, which led the Yanomamis to a "degrading" situation, adding it was in the process of removing illegal miners from the area.

"We also need to find out who is responsible for what happened," he said.

Officials said miners are starting to leave the reservation before the operation expels them.

Brazil's Air Force, which last week declared a no-fly zone over the reservation to stop miners supply routes to clandestine airstrips in the forest, on Monday opened three air corridors for small planes to fly miners out.

The Yanomami have long lived in isolation on the reservation bordering Venezuela. Their mineral-rich lands attracted wildcat miners for decades, especially after a military government built a road through the Amazon rainforest in the 1970s.

When the reservation was marked out and recognized by the government in 1992, authorities mounted an operations to evict 40,000 gold miners.

The miners started to come back in numbers that surged under Lula's far-right predecessor, Jair Bolsonaro, who advocated mining on protected indigenous lands, and whose government turned a blind eye to invasions of indigenous reservations by wildcat miners and illegal loggers.