Medical teams have been sent to northeast India after an outbreak of malaria killed at least 35 people, officials said Thursday.

Teams sent to the state of Assam will perform blood tests and spray insecticides to kill the mosquitoes that carry the illness, Assam Health Minister Bhumidhar Barman told The Associated Press.

He said up to 20,000 people had the illness, but that it was not yet considered an epidemic.

Nine people died of malaria on Wednesday at a government hospital in the town of Lakhimpur, The Sentinel newspaper reported.

Authorities say the strain appears increasingly resistant to the most common anti-malarial drugs.

The heavily forested areas along Assam's border with the Himalayan nation of Bhutan have also been hit by the outbreak, Barman said.

Up to 600 people die every year in malaria outbreaks in India's northeast, an isolated area of seven states.

In 2005, federal health authorities rushed 100,000 insecticide-treated mosquito nets to distribute among the poor in Assam.