The army has found no grounds to the Democrat Party's claims that soldiers are trying to interfere in its preparations for a by-election in Chumphon, according to 4th Army Region commander Lt Gen Kriangkrai Srilak.
He headed a probe into a complaint by the coalition party.
Outlining the complaint, party spokesman Ramet Rattanachaweng said a senior-ranking army officer with the alias "Seh Tor" had led a team of about 100 soldiers in Constituency 1 in Chumphon where a by-election has been called, to pressure residents into voting for a particular candidate.
Army chief Gen Narongphan Jitkaewthae on Saturday instructed Lt Gen Kriangkrai to look into the accusations.
Lt Gen Kriangkrai said yesterday the probe had concluded there was no basis to the claims.
The issue might have been raised by residents, who prompted the Democrats to call for the army chief's help to pre-empt any move that might disrupt a upcoming by-election campaign, according to the commander.
As far as he was aware, the party has not investigated the issue, Lt Gen Kriangkrai said.
"I've issued a swift order that no soldiers under my supervision must interfere in politics. They must remain neutral," he said.
By-elections will take place in Chumphon's Constituency 1 and Songkhla's Constituency 6 to find replacements for Democrat veterans, Chumpol Julsai and Thaworn Senneam, who were stripped of their MP status. No date has been set for the polls.
Meanwhile, Mr Ramet thanked the army chief for investigating the complaint. He maintained the party wanted the by-election to proceed fairly.
The Democrats would remain on alert for any electoral malpractice in local areas and will campaign hard in Constituency 1 on behalf of their candidate.
Mr Ramet earier said the Democrats are fielding Issarapong Mak-ampai in the constituency.