Six Indians were convicted in New Delhi of spying for the United States and were sentenced to three-year prison terms, the Press Trust of India said. Five government officials were found guilty of passing "critical information about India" to the sixth man, P.E. Mehta, a consulting engineer, who said he sold the secrets to U.S. Embassy officials for $390,000. Mehta and the officials--K.K. Sareen and R.P. Varshney, directors of India's Planning Commission, and E.L. Chaudhari, Mahabir Prasad and C.S. Balakrishnan, secretaries to various ministers--were arrested in 1977 but were free on bail during the nine years of court proceedings.