 In 1970, other OPEC states followed suit, leading to a global increase in the price of crude oil.The RCC followed with the Tripoli Agreement of 20 March 1971, in which they secured income tax, back-payments and better pricing from the oil corporations; these measures brought Libya an estimated $1 billion in additional revenues in its first year.Increasing state control over the oil sector, the RCC began a program of nationalization, starting with the expropriation of British Petroleum's share of the British Petroleum-N.B.