Prime Minister Prayut Chan-o-cha said on Wednesday the National Council for Peace and Order (NCPO) had no hand in the share-holding allegation against Future Forward Party leader Thanathorn Juangroongruangkit.
He said the case against Mr Thanathorn, who faces the prospect of being disqualified as an MP, is being taken in line with the constitution, and the regime has no authority over the case, which is being handled by the EC.
Gen Prayut was responding to criticism that the probe against the FFP leader is an attempt to sabotage him politically and thwart the Pheu Thai Party's attempts to form a coalition.
The FFP emerged as a big winner in the March 24 poll, capturing an estimated 80 House seats based on the EC's unofficial results.
However, on March 25, Srisuwan Janya, secretary-general of the Association for the Protection of the Constitution, petitioned the EC to investigate whether Mr Thanathorn was qualified to be an MP.
Mr Srisuwan claimed Mr Thanathorn applied to be an MP candidate while still holding shares in V-Luck Media Co. This could constitute a breach of Section 98 (3) of the constitution, which bars owners or shareholders of media and/or publishing companies from applying to be MPs.
In a statement on Tuesday, the EC said evidence showed Mr Thanathorn owned 675,000 shares in V-Luck Media Co, which runs several media outlets. Mr Thanathorn has seven days to defend himself after receiving the EC's document informing him of the allegations.
Mr Thanathorn said on Wednesday the allegations are intended to sabotage him politically. He vowed to fight the allegations.
On his Facebook account, the FFP leader said he was in Oxford but would cut short his trip and return to Thailand to prepare his defence.
Worawut Butmatr, Mr Thanathorn's lawyer, said the EC's document was sent to the FFP head office and his client's residence, so Mr Thanathorn has until May 1 to submit evidence and counter the allegation.
He said the legal team would call a meeting as soon as Mr Thanathorn returns from his overseas trip this evening.
Meanwhile, a source close to the EC said the FFP leader could face another probe for endorsing a party candidate -- Phubet Henlod -- who was disqualified from the poll by the Supreme Court's Election Division.