Government is planning to divest stake in at least six to seven public sector undertakings(PSUs) in the next 10-12 months,finance secretary Ashok Chawla said on Tuesday on the sidelines of an event organised by Corporation Bank.NHPC,the first IPO by a government owned company in 18 months was subscribed more than 23 times while Oil India Limited,is all set to hit the market in September and bankers estimate it is looking to raise $500-$600 million.Some of other PSUs that have been firming up plans to go public are Coal India and NMDC.