China is poised to invest US$4 billion in Nigerian infrastructure projects in exchange for first refusal on drilling licenses for four oil exploration blocks, the Financial Times reported. It is one of a number of agreements set to be signed by President Hu Jintao during his visit to the African country. Under the terms of the deal, China will buy a controlling stake in a state-run refinery and plow money into a railway line and power plants. In return, China National Petroleum Corp is now in prime position to start exploratory drilling at two sites in the Niger delta region and two sites in the Lake Chad basin. Nigeria, Africa's largest oil producer, has been the chief beneficiary or China's growing interest in the continent's energy assets. Last year PetroChina agreed to pay US$800 million for a 30,000 barrels-per-day supply, while in the last few days China National Offshore Oil Corp sealed a US$2.7 billion deal for a 45% stake in an oil block. In the past, most of Nigeria's oil ventures have been with US and European groups.