* Raises lower end of FY24 profit forecast range

* Posts fourfold jump in half-year profit

* Declares interim dividend of 26 AU cents/shr

Feb 8 (Reuters) - Australia's AGL Energy raised the lower end of its annual profit forecast range on Thursday, betting on higher wholesale electricity pricing and improved plant availability, after it posted a fourfold jump in its half-year profit.

The upbeat results come after the power producer, which also sells retail power to one-sixth of Australians, emerged from a string of prolonged plant outages and volatile energy markets in the corresponding period a year earlier.

"We expect this positive momentum to continue into the second half of FY24 and we are on track to deliver full-year earnings in line with our FY24 guidance range," CEO Damien Nicks said in a statement.

AGL expects its underlying profit to be between A$680 million ($443.29 million) and A$780 million for FY24, compared with its previous range of A$580 million and A$780 million.

For the six months ended December 2023, its underlying net profit after tax was A$399 million ($260.11 million), compared with A$87 million a year earlier. According to Jefferies, the Visible Alpha consensus estimate was A$311 million.

AGL, also the country's top carbon emitter, declared an interim dividend of 26 Australian cents per share, higher than 8 AU cents declared last year.

($1 = 1.5340 Australian dollars) (Reporting by Archishma Iyer, Poonam Behura and Shivangi Lahiri in Bengaluru; Editing by Shilpi Majumdar)