BANGKOK (Reuters) - A Thai court on Tuesday said it would extend a hearing into accusations of graft against Airports of Thailand Pcl (AOT) and duty-free retailer King Power, delaying a decision on whether to take up the case.

A former anti-graft official, Charnchai Issarasenanark, sued executives from both firms last year in a private capacity, accusing King Power of failing to pay the Thai government 14 billion baht ($420 million) from the operation of a airport franchise it was granted in 2006.

The Central Criminal Court for Corruption and Misconduct Cases in Bangkok will hold another hearing session on Sept. 4, a court official said, adding it would summon the president of Airports of Thailand to clarify the board’s duties, its revenues and regulations governing commercial activity.

Airports of Thailand and King Power have previously denied the allegations.

King Power is owned by billionaire Vichai Srivaddhanaprabha and his family. The tycoon also owns English Premier League club Leicester City.

King Power’s franchise is set to expire in 2020 with Airports of Thailand due to hold an auction this year for the license.

($1 = 33.3300 baht)