About 1,500 Sikhs, wearing saffron scarfs and turbans, rallied in sight of the White House yesterday to protest a meeting between President Reagan and Indian Prime Minister Rajiv Gandhi and to charge that 50,000 of their countrymen have been killed by the Indian government.

Marching up Pennsylvania Avenue, the Sikhs -- including groups from Canada, California, North Carolina, Texas and New York -- formed a sea of saffron, the color of the Sikh religious flag, which is "a symbol of rebellion and rejection of Rajiv Gandhi's suppression" of the Sikhs, according to a Sikh leader.

"Sikhs want freedom because India has failed to deliver," said Dr. Hadam Singh Azad, chairman of the Sikh Association of America. "I accuse the Western World of its silence," he said. "How can they tolerate such a violation of human rights?"

As they marched from Lafayette Park to the west lawn of the Capitol, the protesters chanted slogans like "Rajiv Gandhi, a modern Hitler!" and "Rajiv Gandhi: Soviet puppet!"

Men, women and children carried posters with handwritten messages such as "Stop Genocide of the Sikhs in India" and "Live free or die! We want Khalistan!" referring to the Sikhs' desire for an autonomous homeland in India.

Gandhi arrived at the south entrance of the White House, on the opposite side of the building from the protest. The chants from the crowd were amplified by bullhorns through the streets and could be heard in the distance during Gandhi's arrival ceremony.

About a dozen mounted police officers faced the gathering at the park, and although security appeared tight, a U.S. Park Police officer said, "We were expecting a very peaceful demonstration. We are even wearing soft hats. If we expected violence, we would not be wearing these hats."

"We want to tell the kid [Gandhi] that the Sikhs do not approve of his policies of persecution against the Sikhs," explained Buttar Amarjit, a demonstrator from Hartford, Conn. "We also want to tell the American taxpayers to make sure that their dollars are not siphoned to Russia by India."

Some of the protesters wore "Stop U.S. Aid to Russian Ally, India" buttons and "Join the Sant Bhindranwale movement" T-shirts. Bhindranwale was the Sikh leader killed when the Indian army stormed the Golden Temple last June. He is now regarded as a saint by Sikhs.

The final rally at the Capitol began with a prayer followed by a solemn religious song. "We have accomplished a tremendous goal," Azad said. "I am convinced this voice will be heard here as well as in New Delhi.

"I'd like all of you when you go home to have this resolution in your minds: We will not let up. We will not forget [the massacre of Sikhs in the Golden Temple]. We will continue our struggle until such time that basic rights are restored to the Sikhs," he said.

The rally ended with a prayer, after which the Sikhs bent to touch the ground with their foreheads as a mark of respect for those killed at the Golden Temple.