The World Bank's next vice president for development policy will be Albert Fishlow, an economics professor at Yale University and former deputy assistant secretary of State for inter-American Affairs under President Ford, sources said this week.

Fishlow said Monday it was possible that he might fill that post, which is a key one in World Bank policy making, but that it would be "permature" to comment because nothing was confirmed yet. Hollis Chenery, present head of the bank's development policy and research staff, is due to leave in January 1982 to return to Harvard.

Chenery is close to the bank's outgoing president, Robert S. McNamara, and has been responsible for building up its research and policy advisory facilities. He joined as an economic advisor in 1972, and was made vice president for development policy when this post was created in a reorganization of the bank in the same year.

Fishlow's experience has been mainly in Latin America rather than in the poorest areas of the world where the bank's lending is concentrated. He also has worked on foreign debt problems. Many developing nations are deep in dept, particularly after soaring rises in oil prices.

The emphasis of the World Bank's policies could shift markedly in the coming years as a change in the top personnel coincides with considerable pressure to toughen policies towards the developing world. McNamara has been a leading exponent of channeling money to help the poorest in developing nations.

He will be replaced by A.W. (Tom) Clausen, head of Bank of America, who may take a more traditional view of development. Fishlow said this week that he does not know Clausen. If the Yale professor is confirmed in the job, he almost certainly will be working closely with the new president of the bank. To some extent McNamara has used the development policy staff as a secretariat on policy matters.

Banks sources believe that Chenery announced his resignation from the bank early so that McNamara, rather than his successor, could fill the post.

At 45, Fishlow is considerably younger than the departing vice president. He does not have such wide international experience as Chenery, nor is he as well known in development economics. He will be one of 18 vice presidents who head the different sections of the bank.

Fishlow has been at Yale since early 1978. Before that he was at Berkeley for 16 years. In 1975 he took a leave of absence from Berkeley to serve in the Ford administration until the spring of 1976.