En+ owns assets in metals and energy, including a 48 percent stake in Rusal, a Hong Kong-listed Russian aluminium producer, which is a big consumer of hydroelectricity produced by En+'s power companies.
The decision about the IPO may be taken in the next 18 months subject to market conditions, Deripaska said in an interview with Rossiya 24 TV on the sidelines of the St Petersburg International Economic Forum.
The group is not in a hurry to do the deal and may wait for better market conditions as several other Russian firms are expected to do their deals soon, he added.
As of late April, En+ Group planned to raise $2 billion from the sale of a 20-25 percent stake in London and Moscow as early as June, according to sources familiar with the deal.
The funds from the possible deal were expected to be used for refinancing of En+'s $5-billion debt.
(Reporting by Polina Devitt and Anastasia Lyrchikova; editing by Adrian Croft)
