Japan Airlines plans to raise more than 500 billion yen ($6.5 billion) ahead of re-listing its shares as early as September, a source with knowledge of the matter said, marking a sharp turnaround for the carrier following its bankruptcy in 2010.

A government-backed fund overseeing the airline's restructuring has said it would aim to recoup its 350 billion yen investment through a public offering by January 2013, three years after it went under with 2.3 trillion yen in debts.

The public offering is expected to rank as Japan's largest since Dai-Ichi Life Insurance <8750.T> raised 1 trillion yen in 2010, and will likely be carried out against a backdrop of tough industry competition and sluggish economic growth.

The state-backed fund, the Enterprise Turnaround Initiative Corp of Japan (ETIC), is looking at a September to December window to re-list the stock in Tokyo, according to the source, who was not authorized to speak publicly about the deal.

The valuation will be influenced a lot on the level of global stock prices, and right now it's very unclear how stock markets will perform over the next 6 months or so, the source said, adding that 500 billion yen was seen as a minimum target for the offering to get a decent return on taxpayer funds.

Nomura Holdings Inc <8604.T> and Daiwa Securities Group Inc <8601.T> were selected by the ETIC as global coordinators for the public offering in August, a Japan Airlines spokesman said. He declined to comment on the potential size of the share sale.

The carrier emerged from bankruptcy last March after slashing 16,000 jobs, cutting pension benefits and paring its international and domestic routes, and logged a record operating profit of 188.4 billion yen for the 2010 financial year.

Japan Airlines' recovery has been built almost entirely on cost-cutting and comes in the face of high fuel prices and a sluggish global economy, which has crimped travel demand.

Those tough conditions drove American Airlines to file for bankruptcy protection in November, highlighting just how quickly an airline's fortunes can change.

American had offered to invest in Japan Airlines, its partner in the Oneworld Alliance, when the Japanese carrier was heading into bankruptcy in late 2009.

($1 = 76.7400 Japanese yen)

(Reporting by Nathan Layne, Nobuhiro Kubo and Mayumi Negishi; Editing by Joseph Radford and Ian Geoghegan)