A year and a half after Congress made it a crime for U.S. businessmen to bribe foreign officials American executives say that their Japanese, European and Canadian competitors still use payoffs to generate business abroad.

Dozens of American business executives interviewed around the world said they now feel at a disadvantage working in countries where extortion and corruption by foreign officials is commonplace.

Early in 1978, for example, officials of Firestone's subsidiary in Ghana say a local banker indicated a willingness to unblock foreign exchange that the company sorely needed in order to buy raw materials required to run Firestone's local plant.

Firestone officials say they never took advantage of the offer however. The banker, company officials say, demanded a substantial kickback out of the foreigr exchange proceeds.

Firestone's plant in Ghana subsequently was forced to curtail production for several months because of raw materials shortages.

Walter Sterling Surrey, a Washington attorney who is legal adviser to multinational companies, says U.S. companies have experienced many other problems in complying with the 1977 Foreign Corrupt Practices Act.

Surrey says he knows of a case where a Middle Eastern government switched a contract from an American company to a joint venture in which non-American companies had an interest when the U.S. firm refused to pay a bribe.

In another case, he said, two U.S. companies withdrew from bidding for a project in an Asian nation when the government agency conducting the bidding requested a bribe. European and Japanese companies stayed in the competition.

The Foreign Corrupt Practices Act was passed in 1977 after more than 600 companies disclosed to the U.S. Securities and Exchange Commission that they had made hundreds of mil lions of dollars of "questionable payments" to customers and officials abroad.

The disclosures were part of the Watergate-era investigation into secret corporate political "slush funds."

Several U.S. tire multinationals acknowledged payments of this kind.

The SEC charged that General Tire had paid "several million dollars" from concealed overseas funds to Moroccans, Chileans, Mexicans are a Romanian.

Goodyear threatened with an SEC suit for nondisclosure, admitted questionable payments in India, Nicaragua, El Salvador, Taiwan, Aigeria and four unnamed Latin American countries -- including $45,000 "to stop a month-long strike called by a labor union."

The SEC also obtained injunctions against Uniroyal and Firestone in connection with payments related to tire price increases in Mexico.

The antioribery law has become a major source of controversy among U.S. businessmen and government of ficials.

"If we have to bribe in order to do business then to hell with it," says a former business executive who now works for a U.S. government agency.

But SEC officials say enforcement is difficult and that bribes and questionable payments may continue to be channeled abroad through foreign partners, agents or lawyers anyway.

Former SEC commissioner A. A. Sommer Jr. supports the law but says there is ambiguity as to whether a company could be prosecuted if the payment were extorted instead of offered voluntarily.

President Carter said Sept. 26 that the law "should not be viewed as an impediment" to foreign investment.

He promised to have the Justice Department issue guidance on its enforcement policy.

Businessmen and officials say that the fundamental problem cow rests with other governments.

Governments in Europe and Japan have been tough in prosecuting their own officials for taking bribes, but tolerant of payments by their businessmen to foreign officials Developing countries' enforecement of existing anticorruption laws also has been sporadic at best.

A confidential report by the New York-based Business International warns prospective investors in Indonesia:

"The objective reality is that under the present Indonesian administration, there is little likelihood of escaping corruption, though the superficial appearance of corrupt payments may be regularized."

The Indonesian government is undertaking its 10th anticorruption campaign in 12 years, with 1,700 cases before the attorney general. Nevertheless, expert Indonesians have only a vague concept of corruption.

Indonesians who get rich in government are said to enjoy "kena sawabnya" -- "good fortune."