Dec 13 (Reuters) - Australian coal-seam gas producer Senex Energy Ltd agreed on Monday to be acquired by POSCO International Corp in an A$852.1 million ($610.02 million) deal, as the South Korean firm accelerates its expansion into global natural gas exploration and production.

POSCO International, the trading arm of steel giant POSCO , received Senex's approval nASXgtX7Q for the deal after hiking its offer for a third time to A$4.60 a share last month.

POSCO International owns oil and gas stakes in Southeast Asia and is looking to diversify with Senex's gas operations, which supply Australia's tight east coast market and the Gladstone liquefied natural gas (LNG) export project.

In addition to the acquisition, expected to be completed in late March 2022, Senex said it intended to pay a dividend of A$0.05 per share for the half year ending Dec. 31.

The company also noted that Australia's Hancock Energy would acquire a 49.9% indirect stake in it after the deal closes, but said that was not a prerequisite to seal the deal. ($1 = 1.3968 Australian dollars) (Reporting by Tejaswi Marthi in Bengaluru; Editing by Peter Cooney)