Prime Minister Prayut Chan-O-Cha had previously said his government hoped to hold fresh polls around October 2015, after seizing power in a coup six months ago, despite international appeals for a swift return to democracy.
But in an indication elections could be further delayed, Sommai told the BBC he felt polls were at least 18 months away after discussing the issue with Prayut last week.
“As announced by the prime minister, it would take about one year. But, from my feeling, I think it may take, maybe, a year and a half,” he told the British broadcaster.
Junta chief and premier Prayut, who was army chief when he staged the May 22 coup, has said the takeover was necessary to end months of political unrest that left nearly 30 people dead.
But critics accuse the military of using the protests as an excuse for a power grab.
Thailand’s finance ministry Thursday said it could not comment on the BBC interview.
The minister’s comments come days after a junta official told AFP martial law would only be lifted when the country “has peace and order”.
Martial law — imposed by the army two days before the coup — bans political gatherings, allows the detention of dissidents for up to seven days without charge, and permits trials in a military court. -AFP