Labor unions protesting what they called "antiworking-class policies" of Prime Minister Indira Gandhi's government slowed down Indian industry and public services in a 24-hour nationwide strike today that left at least nine persons reported dead in clashes between strike supporters and opponents.

Unions demanding repeal of tough powers assumed by the government last year to prohibit strikes succeeded in shutting down the giant metropolis of Calcutta and much of West Bengal state, India's third largest where the communist-led government had supported the strike call and urged citizens to stay home.

The national broadcast media, which is controlled by the government, claimed that most of the country was open for business and working normally, although at reduced levels.

Since Indian news agencies honored the strike call, an independent check of the government's claims was not possible. But scattered reports revealed that in addition to the deaths, scores of workers were injured as the violence spread through the states of West Bengal, Kerala, Uttar Pradesh, Andhra Pradesh, Tamil Nadu, Karnataka, Tripura and Maharashtra.

The shutdown was called by eight national trade unions affiliated with opposition political parties on the right and left of Gandhi's ruling Congress-I (for Indira) Party. Indian labor unions are commonly linked to political parties, and one major national union affiliated with the Congress-I spurned the strike and urged its members out to work.

The government had cast the strike call as a political challenge by the opposition parties and took strong measures to limit its scope. More than 6,000 union activists were arrested on the eve of the strike in an apparently concerted crackdown, and armed paramilitary units were posted in industrial centers. One state controlled by the ruling party ordered police forces to shoot to kill any persons attempting to sabotage key installations.

The striking unions' main demand was the withdrawal of the 1981 Essential Services Maintenance Act, which enables the government to ban strikes in a broad range of essential services and industries. Another was repeal of India's National Security Act, a controversial preventive detention law under which many of the union activists were arrested Monday.

It was not immediately clear whether the Gandhi government used its antistrike powers today. Government officials have been maintaining that the law is intended only for "extraordinary situations" rather than the on-going strife that marks Indian labor relations. A Gandhi minister noted last week that the government had yet to apply the tough labor law, although 119 major strikes were then in progress.

Opposition leaders said the national strike, their first major confrontation with Gandhi's government, was a success. Production was paralyzed in the Dhambad region, India's main industrial belt, 155 miles northwest of Calcutta, according to Chandra Sekhar, president of the former ruling Janata (People's) Party.

Trains in West Bengal were also reportedly stopped by strikers squatting on the tracks.

The top elected official in West Bengal, Chief Minister Jyoti Basu, reported four people dead and 60 injured after clashes between members of his Marxist Communist Party and Gandhi's party.

At least two people were killed near Benares, in eastern India, when police opened fire on a mob of 1,000 farmworkers, All-India radio reported.

The radio reported another striker was killed in a clash with Congress Party supporters in Alwaye, 340 miles southwest of Madras, and two people were killed and several wounded when police shot at demonstrators blocking highways in Thanjavur, 185 miles southwest of Madras.

In New Delhi, the government kept city buses running and added an extra fleet of 500 for good measure. But attendance in offices was skimpy; downtown wore a deserted, weekend air, and some who set out for work in the morning said they were intimidated into returning home by toughs at bus stops.