International Telephone & Telegraph Corp. today released a court-ordered internal investigation that increased the amount of questionable foreign payments made between 1971 and 1975 from the $8.7 million reported by the company to $13.9 million.

The report also disclosed that the special review committee uncovered an additional $5.7 million in "possible questionable payments" made after 1975.

The report, prepared by two nonmanagement directors of ITT with the help of a team of accountants and attorneys, was filed in U.S. District Court in Washington, D.C.

The investigation was part of the settlement terms of a civil suit filed in 1979 by the Securities and Exchange Commission.

Names of individuals and countries involved in questionable transactions are not identified in the report. ITT says the review committee "recognized the valid legal concerns of subsidiaries operating in countries where the disclosure of business information is not permitted by law."

Federal investigations had disclosed in the mid-1970s that ITT made some $350,000 in political contributions in Chile during the 1970 Chilean presidential campaign. The new report says that none of the newly found payments were "in any way related to Chile nor were any payments made to U.S. federal, state or municipal government officials."

On Aug. 17, 1980, The Washington Post reported that ITT made "millions of dollars" in payments, beginning in 1975, to gain telecommunications sales contracts in Nigeria.

However, the report does not disclose whether those alleged payments were among the post-1975 questionable dealings uncovered by the review committee.

The report does say that the committee investigated the involvement on an ITT European subsidiary in a scandal regarding corruption in the building of the Vienna General Hospital. A criminal investigation followed disclosure in 1980 of the involvement of ITT's Standard Elektrik Lorenz in bribe payments.

The report says that more than

million in questionable payments were made between 1971 and 1979 in connection with the Vienna General Hospital.

The special committee said disclosure of violations of ITT policies on foreign payments after 1975 "raised the question of whether these problems were widespread in the ITT system or were merely aberrations."

Attempting to answer this, the special committee made "test borings" in ITT subsidiaries in Europe, Asia and Latin America. The conclusion from these probes was that questionable dealings are "not endemic to the entire ITT system."