* AGL Energy launches $900 million share sale
* Watchdog okays AGL's A$448 mln power station buy
* AGL rights shares offered at 22 percent discount
* Deal seen going through June 30
* AGL affirms 2012 guidance (Adds detail, comment)
By Miranda Maxwell and Rebekah Kebede
MELBOURNE, May 24 Australia's AGL Energy launched a A$900 million ($875 million) share sale after winning approval from Australia's competition watchdog to take full control of Victoria state's largest power station
The A$448 million plan to take full control of Loy Yang A power station, which provides 30 percent of Victoria state's electricity, also includes Australia's largest brown coal mine.
AGL will buy out Great Energy Alliance Corp, whose shareholders include troubled Tokyo Electric Power Co, which has a 32.5 percent stake, Thailand's Ratchaburi Electricity and Australian superannuation funds.
"There's a little bit of uneasiness with the exposure they've got to this brown coal activity," Peter Strachan, an analyst with Stock Analysis in Perth said.
"At the same time, if you're banking on a change of government by the end of next year, it may well be that the penalties which are involved in running a project like that be lessened somewhat."
A controversial carbon tax on Australian industry starts in July but the opposition Liberal party, which is well ahead in the electoral polls, has vowed to scrap the carbon tax if it wins power. See.
"We have fully factored in the price path for carbon," AGL Chief Executive Michael Fraser told journalists by telephone on Thursday.
Fraser said markets were pricing a 50/50 chance the carbon tax would be reversed by 2014 and said Loy Yang was a high quality generation asset with a long term fuel resource.
"We are buying this at what we think is at or near the bottom of the market," Fraser said.
"We have made no heroic assumptions about wholesale electricity prices," he said, adding AGL expected the market would be very soft over the next few years.
On clinching approval on Thursday, AGL immediately launched a 1 for 6 rights share offer at A$11.60 each, a 22 percent discount to its closing price on Wednesday. Around 78 million new AGL shares, or 17 percent of issued capital, would be issued.
The proceeds would fund the deal and pay off some of the A$2.5 billion net debt owed by the target.
The deal is expected to add to AGL's earnings from fiscal 2013.
The watchdog, the Australian Competition and Consumer Commission (ACCC), said the purchase could go ahead due to strong competition provided by other generators, and potential for new investment.
AGL affirmed it expects underlying 2012 earnings of A$470 million to A$500 million.
Shares in AGL were placed on a trading halt. The stock last traded at A$14.93, off a January closing low of A$13.58.
($1 = 1.0289 Australian dollars) (Reporting by Miranda Maxwell and Rebekah Kebede, Editing by Eric Meijer)