* Tech index touches record high, gains up to 4%

* Miners rally as much as 2%

* Afterpay down 1.2% as annual loss widens

Aug 25 (Reuters) - Australian shares extended gains to a third day on Wednesday on the back of a rally in heavyweight miners due to higher iron ore prices, while the tech sector booked solid gains due to a sharp rise in shares of Wisetech Global.

The S&P/ASX 200 index added 0.4% to end trade at 7,531.9 points, continuing its rebound from a tumultuous past week.

The tech sub-index leaped 1.9% after notching a record high earlier in the session even as the heavyweight buy now, pay later firm Afterpay dropped 1.2% after its loss widened.

Afterpay's drag was far outweighed by a stellar Wall Street session overnight and a 28.5% surge in software solutions provider WiseTech Global.

Aussie miners lent weight, rallying 1.6% with the country's mining triumvirate BHP Group, Rio Tinto and Fortescue advancing between 1.4% and 2.6%.

"Investors are expected to look for clues to the contours of the US central bank's plans for tapering monetary stimulus from Powell's speech at Jackson Hole," Kunal Sawhney, chief executive of Kalkine Media, said.

He added that risk appetite of investors has been lifted by firms reporting share buybacks plus dividend hikes during the current annual earnings.

Additionally, financial stocks rose 0.5% as the big four banks climbed between 0.08% and 1%.

ASX 200 Energy index rose 0.4% led by Viva Energy Group Ltd, up 5.9%, followed by Ampol Ltd, gaining 2.1%, even as oil prices nudged lower.

New Zealand's benchmark S&P/NZX 50 index rose 0.8% to finish the session at 13,173.48 points, on the back of strong earnings by blue-chip NZ firms.

Agribusiness firm Scales Corp was the biggest gainer on the index, up 9.2% on firm half year profit and outlook. (Reporting by Savyata Mishra in Bengaluru; Editing by Krishna Chandra Eluri)