Avner was born on October 23,1913 in Tel-Aviv to Chaya and Michael, 76th infant to be born in the First Hebrew City. Michael was a city-council member during Tel-Aviv’s beginnings. Avner completed elementary school there.
Between 1929-1933 he was an active Hagannah member in Petah-Tikva and Tel-Aviv. Because of his nationalistic views, he joined the Right-wing Hagannah branch, and then Etzel, serving in crucial roles, including directing the Publication and Information Department in the pre-war period. He completed Etzel’s Commanders/Instructors Course 1939, with the Polish Army. When Etzel split he joined Lehi. Until his arrest he served as Commander of Tel-Aviv District. He took part in the money expropriation operation at the Tel-Aviv Leumi bank. Avner married Rivka Schmerling 1938. They had a daughter and two sons, plus six grandchildren. In 1940 he was arrested due to an informant and imprisoned in Akko Prison, Mizra Prison Camp, Central Prison Jerusalem, and finally Latrun. Released after two-and-a half years, he didn’t resume Lehi activities. After establishment of the State he was involved in construction, serving three terms as chairman of the Contractors Association of Tel-Aviv, working in appraisal committees, negotiating with State institutions, and establishing construction companies. He initiated symposiums on housing and land problems, and managed the Builders Residence. He was also an Executive Board member of the Bureau of Co-ordination of Economic Organisations, one of the directors of Bank Otzar Amami, and other similarly oriented projects promoting construction in Israel. As part of his political activities he was general secretary for four years of the ‘Entire Land of Israel Movement’, after the Six Day War. He was active in Gush-Emunim and establishing settlements. During the struggle against the evacuation of Yamit, he remained there for two months as member of the Committee against Withdrawal from Sinai. He was also active in the Committee which opposed the Sabra/Shatila Report. With the Nature Reserves Authority he assisted development of the northern nature Reserves at Gamla, Hula Valley, and others. He participated in the foundation of “Hatchiya” Movement, heading its Tel-Aviv branch.