More than 120 people have been killed by widespread flooding in the western industrial state of Gujarat, India, officials said, with tens of thousands of cotton farmers also suffering heavy damage.

Torrential monsoon rain and flooding in recent weeks have killed at least 300 people in western and eastern states, an official in the National Disaster Management Authority told Reuters in New Delhi on Friday.

"Our teams are working in different parts of India with soldiers to ease the situation," said Deepak Ghai, an emergency room control officer.

More than a million households have been affected, and losses to farmland were being assessed.

The airport in Ahmedabad, the main commercial hub of Gujarat, was partially flooded, forcing airlines to divert flights. More than 150 factories were forced to shut down, said A.R. Raval, a district administrator.

The floods have come at a particularly bad time for cotton farmers in Gujarat, Prime Minister Narendra Modi's home state. Raval said more than 50,000 were struggling to drain water from their land and homes.

Recent downpours have hit cotton and millet in Gujarat and Rajasthan, where farm experts now fear pest infestations.

"Cotton and millet harvests are expected to suffer in about three districts each in Gujarat and Rajasthan, but the biggest worry is that the extra moisture could lead to pest attacks in these areas," Devinder Sharma, an independent farm expert, said.

READ MORE: Scores killed in India floods and landslides

Rains have been four percent above average since the four-month monsoon season began in June, according to the state-run India Meteorological Department.

Floods in India's northeast have killed at least 83 people in the states of Assam, Arunachal Pradesh, Nagaland and Manipur. The downpour triggered landslides, and more than two million people were displaced, according to authorities.

The floods caused by torrential rains across the hilly states of Assam, Arunachal Pradesh, Nagaland and Manipur over the past two weeks, have also triggered landslides.