The major Left trade union, CITU, on Monday urged Prime Minister Manmohan Singh to clarify the reports on PMO’s interferences “favouring” Reliance Industries on the gas pricing related to KG Basin. In a letter to Prime Minister, CITU general secretary and CPI (M) Rajya Sabha MP Tapan Sen said that the role of PMO in supporting Reliance Industries Limited (RIL) to “mysteriously” change the prices in a favourable manner in the KG Basin deal should be probed.