The controversy over office of profit on Thursday night claimed the parliamentary seat of senior Congress leader Karan Singh.

Singh resigned from Rajya Sabha, hours after his party chief Sonia Gandhi resigned from Lok Sabha seat and as chairperson of National Advisory Council.

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Singh, accused by the Opposition for occupying an office of profit -- he is the chairman of the Indian Council for Cultural Relations -- has sent his resignation letter, addressed to Chairman of Rajya Sabha Bhairon Singh Shekhawat.

Singh is also the Chairman of Rajya Sabha's Ethics Committee, which had recommended the expulsion of two members of the upper house -- Chhatrapal Singh Lodh for his involvement in cash-on-camera scam and Sakshi Maharaj for the "misuse" of MPLAD scheme.

Singh claimed the ICCR chairmanship is not an office of profit and that in the past, Atal Bihari Vajpayee and P V Narasimha Rao had occupied this post when they were external affairs ministers.