(Reuters) - General Electric Co's finance arm is in talks to buy Milestone Aviation Group Ltd, as the U.S. conglomerate looks to expand its aircraft-leasing operation into helicopters, The Wall Street Journal reported, citing people familiar with the matter. The purchase price for Milestone could be more than $2.5 billion, according to some of the people, the Journal reported. Milestone, co-founded by NetJets Inc founder Richard Santulli, has announced plans for an initial public offering of stock, according to the report. Buying Milestone, the world's largest helicopter-leasing company by fleet value, would broaden GE Capital Aviation Services' portfolio beyond the competitive plane-leasing business, as it currently owns no helicopters, the Journal said. "As a matter of policy, we don't comment on market rumors or speculation," a spokeswoman for Milestone Aviation said. Officials at General Electric were not immediately available for comment. (Reporting By Manya Venkatesh in Bangalore; Editing by Simon Jennings)