Congress President Sonia Gandhi is likely to address the United Nations on October 2, the birth anniversary of Mahatma Gandhi which will be observed from this year onwards as International Non-Violence Day. Sonia and Prime Minister Manmohan Singh had written letters to some 150 heads of state and government seeking their support to the idea of 'Satyagraha', which the Mahatma had launched 100 years ago. The party had earlier this year held an international conference to commemorate the centenary of the launching of Satyagraha. The idea of promoting a resolution in the UN seeking commemoration of October 2 as International Non-Violence Day originated during the conference held here earlier this year, the Press Trust of India reported today.