Montek Singh Ahluwalia, deputy chairman of Planning Commission, todayfavoured a hike in fuel prices to keep pace with the rising international oil prices."Its simply not sustainable to enter into an era of high oil prices without charging economic price," Ahluwalia said on the sidelines of a conference of secretaries on private-public partnership in infrastructure projects."When we do that (price hike), we will have to identify the customers who need to be protected. The commission is sure of a few oil products' sensitive nature and price hike there has to be reasonable. Subsidies, too, have to be reasonable related to other forms of subsidies. It is a complex balance," Ahluwalia said while seeking tax cuts for oil companies.Discussions are being held between the finance ministry, the petroleum ministry and the Prime Minister himself to find a solution to the issue.