WARSAW, FEB. 20 -- The Polish government and officials of the Rockefeller Foundation today announced the creation of a foundation meant to stimulate agriculture here in another small step by Poland toward winning badly needed western financial support.

The foundation, started after several years of negotiations between Rockefeller Foundation officials and the government of Gen. Wojciech Jaruzelski, will initially invest $2.4 million raised from western commercial banks in a project to increase breeding of Polish pigs and increase ham exports to the United States.

Proceeds from the venture will be used for other technical, educational and commercial projects meant to improve Polish agriculture, a key part of the nation's economy that is largely privately owned but backward by western standards. The nonprofit foundation, set up under Polish law, will be managed by a blue-ribbon council including prominent American and West European agronomists and businessmen as well as a minority of Polish experts.

Foundation officials, who participated in a ceremonial inauguration today at Warsaw's Royal Castle, described the project as a potential model for how Poland, burdened by a $39 billion foreign debt, could begin to attract new foreign investment from the West. Lending to Warsaw by western governments and banks was halted after the imposition of martial law in 1981 and remains almost nonexistent.

"The amounts of money being raised by the foundation are not significant in relation to the size of Poland's debt," said Leon Irish, a council member and organizer of the foundation, at a press conference. "But the foundation can be important as a path-breaker and a model on how things can be eventually done on a much larger scale to bring new funds into Poland."

The foundation's establishment comes several months after authorities granted final approval to another foundation created by Poland's Roman Catholic Church to support private agriculture. That project is backed by a $10 million appropriation from the U.S. Congress.

Both initiatives were stalled for years in negotiations as Jaruzelski's government hesitated to accept projects independent from state control and funding. In the end, the church program was scaled down but remained independent of the government, while the Rockefeller-backed foundation will have to obtain approval from the Ministry of Agriculture before proceeding with any specific activity.

The first project planned by the new foundation will involve importing high-quality western feed to improve the productivity of Polish pig farmers. The foundation will also arrange the import of modern packaging materials and machinery for the state food processing firms.

The foundation, headed by U.S. agronomist Norman Borlaug, estimates that over five years it will increase supplies of pork for sale in Poland by 30,000 tons annually, while ham exports to the United States will increase by 5,000 tons, or about 14 percent.