UNITED NATIONS, N.Y., June 11.-An official of the United Nations who has just returned from Pakistan said today that President Mohammad Agha Yahya Khan's Government would distribute United Nations relief supplies in East Pakistan.

Ismat Kittani, an Assistant Secretary General, said that he did not yet know how assurances could be obtained that the aid would actually reach the East Pakistanis but he indicated that he was counting for verification on foreign officials and on the United Nations staff workers who are returning to Jobs here.