A Houston engineering company has said in court papers here that "all or a portion" of $10.1 million it paid in commissions to obtain the contracts for two huge timber projects in Iran may have gone to Prince Abdul Reza Pahlavi, brother of the deposed shah.

The payments, made by a subsidiary of International Systems and Control Corp. between 1972 and 1977, went into five bank accounts in Geneva, Paris and New York City.

In a telephone interview yesterday, ISC's senior vice president, Herman M. Frietsch, said there was no direct evidence that the prince got the money. But Frietsch added: I'm not denying that the prince was involved and that he used his influence."

The ISC case and the light it sheds on royal involvement in the Iranian economy is significant because the new regime has charged that deposed shah Mohammad Reza Pahlavi and his relatives "plundered" the country and shifted billions of dollars abroad for their personal enrichment.

The Iranian government filed suit in New York City Wednesday alleging that the shah and his wife had diverted at least $20 billion in Iranian government funds to their personal use through the Pahlavi Foundation of Tehran and five other foundations.

Banking and economic officials in Iran this week intensified their efforts to obtain detailed records of the royal family's financial activities.

Preliminary findings in Iran show that some members of the family transferred millions of dollars out of the country in the final weeks of the shah's rule. However, the ISC case, as well as information provided by informed U.S. sources, indicates that the royal family's involvement in the nation's economy was far more sweeping than has yet been shown.

"The experience was that members of the royal family weren't in competitive fields of the economy." Frietsch said yesterday.

For example, another of the Shah's brothers, Prince Gholam Reza Pahlavi, held an interest in the John Deere tractor assembly company, and was involved in aluminum and textiles.

Prince Abdul Reza's key role in decisions affecting Iran's burgeoning forest products industry emerges in documents filed in District Court here in connection with a Securities and Exchange Commission suit against ISC. The SEC charged the company in July with paying at least $23 million in bribes in Iran and six other foreign countries.

The internal company documents chronicle the successful efforts of ISC's Canadian subsidiary, Stadler Hurter Ltd. (SHL), to become prime contractor for the Gilan and Mazandaran timber, pulp and paper projects.

Contracts totaling $243 million eventually were awarded to SHL. The documents show that the prince played a key role in helping SHL win approval despite competitive challenges from Japanese and other groups.

One of those designated in 1972 by SHL to receive a commission payable to a numbered bank account in Paris was a Hashem Naraghi, described in an affidavit by an SEC investigator as the prince's associate.

In an April 1974 memorandum, SHL was advised that "the prince keeps complaining about certain delays in our payments."

In November of that year, Max Zeier, a Swiss citizen representing SHL in Iran, wrote that "our performance also includes that we meet our financial obligations toward the prince punctually."

Zeier's reports describe how the prince intervened in November and December 1974 during a crisis caused by an unexpected challenge, by an unidentified competitor to SLH's bid for the Mazandaran pulp and paper project.

At one point, the minister of agriculture threatened to turn over to the shah evidence of "bribery" and an "unethical attitude" by SHL, Zeier reported. However, the difficulties were resolved after a meeting between the prince and the minister of agriculture. On Dec. 21, 1974, SHL received the $143 million Mazandaran contract with the apparent approval of the shah.

In March 1975, the shah initiated a major campaign against corruption and, among other things, ordered an investigation of the $82 million contract awarded to SHL in 1973 for the Gilan project.

On March 7, Zeier, quoting SHL's local agent, Shamsedin (Shamse) Golestaneh, reported that the prince was told by the shah "at the very last minute" that a large industrial project in the Tehran area had to be awarded "in a different way."

"According to Shamse, this meant loss of income to the prince of 150-210 mio. [million] dollars. After having lost the aforementioned project, the prince was told that he would be compensated by the project presented by ISC in the Persian Gulf," Zeier wrote.The Persian Gulf project, which was to have involved mineral development, never materialized, ISC's Frietsch said yesterday.

Efforts to locate Prince Abdul Reza this week were unsuccessful. Telephones once listed to an S. Golestaneh in Geneva, Bal Harbour, Fla., and Paris were no longer in service.

Earlier, the SEC had obtained an order restraining ISC from disposing of any of its assets pending the outcome of the suit. It also sought an injunction against the company's making payments in violation of the Foreign Corrupt Practices Act.

In its response to the government's complaint, ISC's attorneys claimed that payments to Golestaneh and Naraghi did not violate the act, since they were commission fees to private Iranian businessmen who were not employed by the Iranian government. Also submitted in ISC's defense was a statement from the Iranian Ministry of Justice saying Prince Abdul Reza was "engaged in private business for his own commercial purposes."

"Everybody we knew who was competing for business over there had some arrangement," said Frietsch. "You had to have a local agent just to get into the game."

He said the Gilan project, now stalled, is 95 percent complete and Mazandaran is 20 percent finished. He added that SHL is owned $25 million on the Iranian projects. Recently SHL changed its name to Kedzep and filed for voluntary bankruptcy in Canada.

The chronicle of SHL's activities in Iran shows that the company's fortunes inproved dramatically in July 1972, two months after it was acquired by ISC.

In January of that year, the SEC investigator's affidavit says.SHL's president, A. M. Hurter, considered the Gilan project "lost to the Japanese." But on July 9 Hurter met Prince Abdul Reza to make new proposals. Three days later, Golestaneh met with the prince.

On Aug. 4, SHL gave Naraghi, described as "one of the prince's associates," an "irrevocable letter of undertaking" promising to pay 3 percent of the Gilan contract price into a numbered bank account of the First National City Bank [now Citibank] in Paris.

On Aug. 11. SHL, at Golestaneh's request, issued another letter to a Liechtenstein company called Amirco Etablissement, designating it to receive 4 percent of the contract price if SHL got the award for Gilan.

On Oct. 11, Golestaneh instructed SHL to pay $250,000 to the account of Parviz Sepahbodi, of the Ministry of Economics, at the Manufacturers Hanover Trust Co. in New York City.

ISC acknowledged in its response to the government's suit that it paid a total of $10.1 million to numbered accounts abroad dedignated by Golestaneh. One was the Citibank account in Paris. The other two were at the Swiss Bank Corp. in Geneva and the First National Bank of Chicago in Paris.

"All or a portion" of this money may have gone to the prince, ISC said in its response. "There's no way to tell who finally got it," Frietsch said yesterday.

Golestaneh, 54, was reported to have a master's degree from Columbia University and to have served in the Iranian diplomatic corps in London and the United Nations before going into private business.

ISC said its response that the Canadian Embassy in Tehran was aware that SHL was using Golestaneh as its agent and that a 1971 embassy telex message showed that the embassy knew that commissions were to be paid.

ISC aslo acknowledged that it paid $1.2 million to a numbered account at the Swiss Credit Bank, "all or part" of which may have gone to Sidney Askari, an Iranian who served as president of Technolog, the firm that was the official engineering consultant to the Iranian government.

As president of Technolog, Askari was central to the contract awarding process in the forest industries projects, exhibits on file with the court show.

On July 23 and 24, 1974, according to SHL documents, Askari was present at a company meeting in Zurich in which it was agreed to submit a $9 million "escalator" claim on the Gilan project to Askari at Technolog.

On Dec. 15, 1974, the company issued a letter agreeing to pay $1 million in commissions to two of the Swiss bank accounts designated by Golestaneh, in case the $9 million escalation cost were approved.

However, the SEC affidavit charges, the plan encountered difficulties when, in March 1975, Askari was asked to resign and the shah ordered an investigation of the Gilan contracts.

The SEC charged that the true nature of the escalator proposal was, in part, an attempt to generate revenues to pay commissions.

Meanwhile, the company has won the Mazandaran contract, but only after the difficulties with the ministry of agriculture had been cleared away. At one point, Prince Abdul Reza was reported "angry" that the SHL bid may have been "exaggerated." After the bid had been reduced, however, "the price, as agreed with Sid Askari, was approved by the prince," SHL's Zeier reported on Dec. 9, 1974.