The heads of the United Nations World Food Program and U.N. children's agency UNICEF have privately appealed to Israeli Prime Minister Benjamin Netanyahu for help "alleviating the suffering of countless civilians" in the Gaza Strip, West Bank and Lebanon, according to a letter seen by Reuters on Monday.

"Effective and meaningful humanitarian action is possible with your political will and commitment," wrote UNICEF Executive Director Catherine Russell and WFP Executive Director Cindy McCain in the previously unreported letter dated Oct. 11.

Netanyahu's office did not immediately respond to a request for comment on the letter.