Monsanto Co. contributed $7,500 to fight an anti-nuclear-power referendum in California last year, helped bankroll a publicity drive for the St. Louis zoo in 1971 and picked up the tab for a $50 contribution to the Caribor County, Idaho Republican party.

The multinational chemical company also kept two foreign customs agents on its payroll at $124 a month, routinely kicked back 5 per cent of sales by a subsidiary to one foreign government and made secret political contributions in Australia.

The previously undisclosed payments are detailed in Monsanto reports to the Securities and Excahnge Commission which were made public yesterday. The reports were released after Freedom of Information Aclawsuits were filed by The Washington Post and The Wall Street Journal.

The Monsanto documents provide some new details of the company's previously reported $461,000 in illegal "questionable payments" abroad and give a glimpse of its corportate spending for domestic politics.

Details of the Monsanto payments were assembled by teams of lawyers and auditors who interviewed 120 workers and examined books in 19 countries.

In their report, Monsanto lawyers and auditors did all the domestic political contributions were legal, save for a few made by executives of branch facilities without the knowledge or approval of corporate headquarters in St. Louis.

The report shows $3,800 in political contributions were made with Monsanto funds by the unidentified manager of an unspecified plant in Idaho.

The company said a 1975 audit revealed "the plant manager had improperly diverted, contrary to company policies, relatively small amounts of company funds over a period of years to a personal checking account."

"The plant manager was demoted" and promised to repay the company, the report said.

The money, from vending machine profits and sales of scrap, then was used to make 20 political contributions over a four-year period.

The $2,425 in contributions to state candidates in Idaho were legal under state law, the rerport said; the $1,375 in federal contributions, were reported to the Justice Department, whick declined to prosecute because the company funds were repaid.

Among the Idaho political contributions was $750 to the 1974 gubernatorial campaign of Cecil Andrus, now the Secretary of Interior. Another $500 of Monsanto's money went to Idaho Lt. Gov. Jack Walsh, Andrus' opponent. County and state Republican and Democratic groups in also received funds.

Monsanto's foreign political contributions included $9,000 to two Argentine parties in 1972 and 1973 and $16,000 to Australian parties over a five year period ending in 1975. Corporate political contributions are legal in both countries, the Monsanto report said.

However, the Australian political gifts were made by a Monsanto subsidiary through an Australian law firm to keep them secret, the report acknowledged. Monsanto's secret gifts included more than $7,000 to Australia's Country Party, $1,400 to the Labor Party, $5,900 to the Liberal Party and $1,500 to the Democratic Labor Party.

Though the report on foreign and domestic payments had been demanded by government investigators, Monsanto still refused to name the countries in which some under-the-table payments occurred, saying it feared the payments would be revealed by an F0I suit.

Monsanto listed thousands of dollars in payments in one un-named country in which customs personnel routinely were paid for handling the company's shipments.

Two customs men were paid $124 "for services, transportation and lunch" every month for three years and also got about $5 per shipment as "an escort fee."

In the same country, Monsanto paid tips ranging from $36 to $48 per shipment on every shipment coming in or out of the plant of a Monsanto subsidiary. The company estimated those "clearing and handling" payoffs totaled as much as $48,000.

In another country, a firm controlled by Monsanto gave kickbacks equal to 5 per cent of sales of one product. The kickbacks went to a government purchasing official on government purchases, and to private contractors who held government contracts. The kickbacks ranged from $3,000 to $6,000 a year.

Among other domestic contributions, Monsanto on 12 separate occasions gave funds to St. Louis Chamber of Commerce groups campaigning on issues that were bofer the voters in the company's home town.

Starting with $5,000 to support a campaign to raise taxes for the St. Louis Zoo and museum, in 1972, Monsanto poured nearly $50,000 into the local chamber's Civic Development Fund. Monsanto money backed water pollution control bonds, a uniform building code, minimum standards for police, higher school taxes and several public works bond issues.

Monsanto officials declined to comment on the detailed contributions, but one company official described the St. Louis spending as "corporate good citizenship."

In California, Monsanto gave money to two groups opposing a referendum to restrict nuclear power, the documents showed. The company said $5,000 went to Citizens for jobs and energy and another $2,500 to the No on 15 committee, Californians against Nuclear shutdown. The anti-atom proposition was defeated last year by California voters.