A group of U.S. Congressmen have invited Indian Prime Minister Morarji Desai to appear before the Congress to explain his government's reasons for not adopting the nuclear safeguards that the United States demanded.

Desai made "a very strong case" for India's position "so we invited him to come spell it out," said Lester Wolff (D-N.Y.), leader of the delegation from the House subcommittee of Asian and Pacific Affairs.

When President Carter visited India earlier this month he tried in vain to get Desai's agreement on outside inspection of India's nuclear program.

According to sources in the 11-member House group, Desai argued that the Nuclear Nonproliferation Treaty, in which the safeguards are embodied, discriminates against nonnuclear nations.

Desai has said that he was willing to open up India's nuclear installations for foreign inspection under certain conditions, although still not signing the Non-Proliferation Treaty. His terms are that the United States and the Soviet Union reach agreement on a comprehensive test ban treaty and that the two superpowers put a ceiling on their stockpiles of nuclear weapons and establish a target date for reducing the number of those weapons.

Under U.S. law, India risks a cutoff of U.S. uranium fuel for its Tarapar reactor for failing to accept the safeguards.

"There are very serious questions within Congress on this matter," Wollf told a news conference. "We have assurance from Mr. Desai that he would rather resign than contemplate using nuclear weapons. He said he would like to come before Congress to explain his views . . . He was sure he could convince us he was right."

When India set off a nuclear explosion in 1974, it came under interna-material from its nuclear power program to develop nuclear weapons in violation of agreements it had signed.