Embattled Deputy Prime Minister Prawit Wongsuwon said on Fridayy it was up to the National Council for Peace and Order (NCPO) to decide whether to reveal the names of the panellists responsible for picking senators.
"Their names can be revealed," Gen Prawit, who chairs the selection committee, told the media on Friday.
"However, I don't know when that will happen as that falls under the jurisdiction of the NCPO, which was obliged under the charter to pick the [250] senators," he added.
Gen Prawit also chairs the NCPO's advisory committee.
He made the remarks after Pheu Thai secretary-general Phumtham Wechayachai on Wednesday urged Gen Prawit to disclose the names in the interests of transparency.
Mr Phumtham claimed some of the senators were also on the committee, implying they helped to select themselves.
Gen Prawit was lambasted by local media and politicians after reports emerged this week that the committee was stocked with figures who have close links to the military government.
No fewer than 101 of the 250 senators were found to have military or police backgrounds, one is the younger brother of Prime Minister Prayut Chan-o-cha, and three are siblings of deputy prime ministers.
Gen Prawit sternly denied the accusation that the selection process had been riddled with nepotism.
"The selection process was handled transparently and in compliance with the charter," said Gen Prawit, whose younger brother Gen Sittsawet Wongsuwon now sits in the Senate.
Air Vice Marshal Chalermchai Krea-ngam, a younger brother of Deputy Prime Minister Wissanu Krea-ngam, was also selected. In defending his appointment, he cited his previous experience in the Upper House from 2011-14. He also sat on the National Reform Steering Assembly.
"I would say I have a strong will to work and I'm unfazed by pressure," AVM Chalermchai said.
He denied speculation of a rigged Senate, adding, "I don't believe anyone would be able to order us which way to vote."
The Senate will serve a five-year term. Its first task will be a joint sitting with the new House of Representatives to vote for the nation's next premier -- widely expected to be Gen Prayut.
Gen Prawit also refused to comment on the recent decision by the Election Commission to forward an alleged shareholding-violation case involving one of Gen Prayut's rivals for the role of prime minister to the Constitutional Court for a ruling.
Thanathorn Juangroongruangkit, charismatic leader of the Future Forward Party leader, is the accused.
