THE HAGUE, 15 May— Saudi Arabia has reaffirmed its commitment to the Treaty of Chemical Weapons Ban, while participating at an international conference of the signitaries of the treaty which opened here yesterday. The Kingdom believed in peaceful coexistence of all countries, preservation of their achievements and potentials and prevalence of peace and security, said Suleiman Al-Khowaiter, head of the Saudi delegation to the conference. The Kingdom is keen on joining treaties and pacts aimed at strengthening peace and reducing the chances of wars using nuclear, chemical and biological weapons.