Nigeria's state oil company warned investors interested in three shallow water oil blocks offered for sale by Chevron that buyers may lose the right to operate them. U.S.-based Chevron is selling minority stakes in joint ventures that operate five oil blocks. The majority owner is the Nigeria National Petroleum Corporation (NNPC). Nigeria wants more direct ownership of its oil and gas through NNPC or local firms, leading several oil majors including Chevron to dispose of assets in Africa's top oil and gas producer. NNPC published a notice in local newspapers saying that there had been a "recent high level of interest shown by various investors in the ongoing divestment program for OMLs 52, 53 and 55 by Chevron Nigeria". It reminded those considering investing that, although Chevron currently operates the blocks, the state oil firm has the right to take over the operatorship as majority shareholder. Chevron owns 40 percent of the blocks and NNPC 60 percent. "Chevron shall cease to be the operator upon assignment of their participating interest," it said. "Therefore prospective buyers should note that automatic operatorship does not come with the acquisition of any of these blocks." Not having operatorship poses significant risks for would be investors in the fields, not least that the NNPC's development subsidiary, NPDC, lacks the finance and expertise. It has usually had to call in a third-party operator anyway. The notice seemed calculated to avoid messy tussles that ensued when Shell sold some oil blocks two years ago.