Future Forward Party leader Thanathorn Juangroongruangkit has accused the Election Commission of trying to sabotage him politically.
He posted the comment, and a short video clip, on Facebook late on Tuesday night after the EC accused him of wrongfully holding shares in V-Luck Media Co. The law bans MPs from holding stock in media companies.
"Do not worry. My morale is strong and I believe in my innocence. This case is intended political sabotage. I will defend it with sincerity," Mr Thanathorn said on a post datelined from Oxford.
He also said he was on a trip to Europe but would advance his scheduled return to Thailand to Thursday, and would give his explanation directly to the EC.
In a statement on Tuesday, the EC said evidence showed Mr Thanathorn owned 675,000 shares in V-Luck Media Co.
Mr Thanathorn owned V-Luck Media Co Ltd, publisher of the now-folded WHO! people and lifestyle magazine. He said he had sold the shares on March 8 last year to his mother before applying to register as an aspiring MP, and showed evidence of the transactions on his Facebook account.
However, some media outlets questioned whether the share sale actually occurred after the March 24 polls this year, leading to the EC's investigation.
In its statement, the EC secretary-general said the commission would inform Mr Thanathorn of the accusation, examine the evidence and hear witnesses. Mr Thanathorn has seven days after being informed to submit evidence countering the accusation.