NEW DELHI, India (AP) _ Former Prime Minister Chaudhary Singh, a champion of India's farming community, died Friday after a long illness. He was 84.

According to doctors, Singh died of cardiac arrest at his residence.

The son of a farmer, Singh's long political career depended on the support of peasants in Uttar Pradesh and Haryana states in northern India.

Singh, a bitter critic of the late Prime Minister Indira Gandhi, joined hands with her in 1979 when she was out of power to topple the Janata (People) Party's administration and form a new government with her support. He served as prime minister for less than six months.

The government of Prime Minister Rajiv Gandhi, son and successor of the assassinated Indira Gandhi, declared a four-day national mourning period for Singh. All offices across the country were closed Friday.

Singh opposed the development of heavy industry and favored small-scale, rural-based factories and moderately sized owner-tilled farms.

Born in Uttar Pradesh, Singh studied law and entered politics in 1929 during India's struggle for independence from Britain. Until his election to the national Parliament in 1977, Singh devoted himself to regional politics. Twice he served as Uttar Pradesh chief minister.

During 1977-79, he served as India's interior minister.

Singh is survived by his wife, Gayatri Devi, a son and five daughters.