* Annual underlying profit misses forecasts

* Sees 2023 earnings higher, but withholds guidance

* Share price slides 7%

MELBOURNE, Aug 18 (Reuters) - Australia's Origin Energy Ltd posted a 30% jump in annual underlying profit on Thursday but sharply missed forecasts and warned of continuing uncertainty for fiscal 2023 earnings, sending its shares down 7%.

While benefiting from soaring gas and oil prices on its liquefied natural gas (LNG) exports, Australia's no.2 power producer withheld guidance for 2023 due to extreme local gas and power price volatility and coal supply problems to its Eraring power plant.

Chief Executive Officer Frank Calabria said he was surprised by the share price slump, even as the company broadly flagged that earnings would grow in 2023 and 2024. He said the range of potential outcomes was too wide to give sensible guidance.

"(We) feel that the trajectory over the next couple of years is up," Calabria told analysts on an earnings call.

"And that's what we're trying to convey today. I've obviouly not been successful in doing that."

Origin's underlying profit rose to A$407 million ($282 million) for the full-year ended June 30, from A$314 million a year ago, but missed Refinitiv IBES estimates of A$537.5 million, hit by lower earnings in its energy markets unit.

"No guidance for FY23 EBITDA in the Energy Markets division will disappoint the market," UBS analyst Tom Allen said in a note.

Origin said underlying earnings were expected to be higher, "driven by growth in earnings from the gas business, while electricity gross profit is expected to remain suppressed", as it still faced risks of not receiving enough coal for its Eraring power plant, which would expose it to spot coal prices.

Origin declared a final dividend of 16.5 Australian cents per share, compared with 7.5 cents a year earlier and analysts' consensus of 15.2 cents.

The company said it would not step up share buybacks until the earnings outlook was clearer.

($1 = 1.4418 Australian dollars) (Additional reporting by Roushni Nair and Himanshi Akand in Bengaluru; Editing by Shailesh Kuber and Rashmi Aich)