Mineral-rich states - Jharkhand, Orissa and Chhattisgarh - have sought the intervention of Prime Minister Manmohan Singh in fixing royalty of minerals on an ad-valorem basis and continuing their special powers to allocate mines to prospective investors.In a joint representation to Singh, the Chief Ministers of the three states, along with the mines minister of Rajasthan, stressed on increasing the royalty on minerals, particularly iron ore and coal, by fixing it on an ad-valorem basis.They suggested that the royalty be fixed on 20-25% of the sale price as was done for crude oil in 2004.The states impressed upon the need to extend support to the on-going industrialisation in the mineral-bearing regions for creating employment opportunities and increasing revenue generation.They urged the Prime Minister that the special powers granted to them should be continued so as to enable them to attract investors.The chief ministers advocated a freeze on the current level of iron ore exports, and emphasised that a mechanism be worked out to reduce their exports to ensure availability of ore to domestic steel producers at competitive prices.