Indian President's candid warnings about corruption riles Mrs. Gandhi

The outgoing President of India has added his voice to a chorus of concern about India's declining public morality, warning it could lead to consequences ''too frightening to contemplate.''

''Unless we take immediate action to arrest the disregard of moral values in public life, people's faith in our political system will be undermined with consequences which are too frightening to contemplate,'' said Neelam Sanjiva Reddy, the Indian head of state.

Mr. Reddy's sobering assessment came in a nationwide broadcast Jan. 25 on the eve of Republic Day, the official national day marking the adoption of India's 1950 Constitution. It follows an avalanche of charges and warnings, by both pro- and anti-government figures, that official corruption is soaring, violence is spreading, and Indian political institutions are in an advanced state of decay.

With only six months left in his five-year presidential term, President Reddy has become more outspoken in his criticisms of the government's seeming inability to check caste and communal violence and extend the benefits of development downward to India's poorest and weakest.

His candid comments have irritated Prime Minister Indira Gandhi and reportedly provoked her to complain that he was encouraging her political opponents.

A recent Bombay high court ruling that one of Mrs. Gandhi's hand-picked state chief ministers had been peddling scarce government-controlled cement for ''donations'' to his privately run trust funds has fueled concern about official corruption, now widely believed to be at an all-time high for post-independence India.

Opposition politicians had a field day with the trust fund issue, but Mrs. Gandhi dismissed their charges as ''malicious and vicious'' attempts to demoralize the Indian people and detract from her government's accomplishments. She also termed corruption a global phenomenon from which India was not immune.

But much of India sat up and took notice at a particularly potent recent charge that ''corruption has spread to every part of the governmental apparatus.'' It came not from an opposition politician but from Mrs. Gandhi's second cousin, B. K. Nehru, former Indian ambassador to Washington and London who now serves as governor of the Indian state of Jammu and Kashmir.

''A large number of politicians and ministers are corrupt, corruption is universal in the lower ranks of the public services, it has affected the middle ranks as well, and is now infecting the apex of our administrative structure - the All-India Services - who used at one time to be, like Caesar's wife, wholly above suspicion,'' said Mr. Nehru.

''It is interesting, as an index to the kind of person who now wields power, '' he added, ''that in one particular state, no less than 30 percent of the legislators are involved in criminal cases of one type or the other.''

Analysts across the political spectrum have complained that politicians of all parties see public office as an opportunity to enrich themselves through the sale of patronage jobs, government-controlled commodities, and the many permits needed to do business in India's mixed economy.

Although President Reddy did not specifically cite official corruption, he pointedly noted the financial sacrifices made by participants in India's struggle for independence from Great Britain ''without expecting any reward for themselves in their lifetime.''

''What we find today is the very antithesis of the noble spirit that animated the nation only a few decades ago,'' said Mr. Reddy. ''Why is it that this permissive attitude has overtaken our society in the short span of a few decades?''