Lattice sale would be top Australian oil, gas deal since 2015...

• Lattice sale would be top Australian oil, gas deal since 2015
• Private equity seen circling
• Origin favours IPO, but analysts see trade sale as less risky

Australia's top energy retailer Origin (ORG) has drawn interest from at least five potential bidders, including China's Fosun International <0656.HK>, for A$2.0 billion ($1.5 billion) worth of oil and gas assets it aims to spin off, sources said.

Origin said in December it was going to put its smaller Australian and New Zealand gas fields in a unit, dubbed Lattice Energy, to be spun off in an initial public offering (IPO) this year to help it cut debt and boost returns.

But after receiving approaches for some of the Lattice assets, Origin Chief Executive Frank Calabria said in March the company was willing to consider a trade sale, in what would be the biggest oil and gas deal in Australia since Apache Corp sold its Australian assets in 2015.

Origin has opened Lattice's books, with bids due in June, and is likely to decide whether to float the business or sell it after releasing full-year earnings in August, people familiar with the process said. It is being advised by UBS, Macquarie and Bank of America Merrill Lynch.

Analysts at Royal Bank of Canada and Citi value Lattice at A$2 billion and A$2.3 billion, respectively, including debt, on a discounted cash flow basis.

"Origin has set the bar quite high. It'll be interesting to see if anyone gets there," said one banker not directly involved in the process, when asked if the business was likely to fetch more than A$1.5 billion.

Australia's Beach Energy (BPT) is one of the interested parties and could be the bidder to beat, as it is the biggest of the producers in the fray, the sources said. Lattice, with annual output of around 13 million barrels of oil equivalent, would more than double Beach's production.

But even for Beach, with a market value of A$1.2 billion, Lattice would be a huge bite.

Beach declined to comment on whether it was bidding, but the company has said in presentations it is reviewing several "inorganic growth" opportunities.

Fosun International, which took over Roc Oil in Australia in 2014, is looking, the banker said.

Private firm Questus Energy, run by former Roc Oil and Shell executives and backed by UK-based Intermediate Capital Group , is also in the running, a second banker said.

Origin declined to comment beyond what it has announced. Fosun and Questus did not respond to requests for comment.

Bankers expect private equity firms that have long eyed Australian oil and gas assets to team up with local producers to bid.

Senex Energy (SXY) is expected to work with its stakeholder, U.S. private equity firm EIG Global Energy Partners. KKR is seen lining up with AWE Ltd (AWE), two bankers said. All four firms declined to comment.

Private equity fund Lone Star, which was rebuffed in a bid for AWE last year, declined to comment on whether it was looking at Lattice.

All the sources did not want to be named as the process is confidential.

Private firm Pathfinder Energy, which some assumed would be in the race, told Reuters it is not bidding.

While Origin has said it would prefer an IPO, some analysts say a trade sale would be less risky.

"There is a real cost to having exposure to equity markets and the variability of the market," said RBC analyst Ben Wilson. ($1 = 1.3452 Australian dollars)