The army says military officers are free to cast their vote for whichever party they want and they are not under any order to vote for any particular politician.
As thousands of soldiers took part in advance voting Sunday, army spokesman Winthai Suwaree said it is "impossible" and illegal to command officers to vote for any particular politician since votes are cast privately at secured polling booths.
Most soldiers who casted their votes were seen wearing casual clothes and sports attire.
Col Winthai made the comment after critics questioned if the soldiers' votes were influenced by their commanders.
Political observers are keeping a close watch on the poll, which is the first poll to take place in about eight years since the Pheu Thai Party won the 2011 election, which saw Yingluck Shinawatra, Thaksin's younger sister, become the country's top leader.
She was in power for less than three years before her government was toppled in the 2014 coup following a political stalemate that led to the establishment of the military government.
"The army follows the government's policy to support this election," Col Winthai said.
"In doing so, it encourages officers and their families to vote with their own free will."
Many officers, including those stationed in the deep South and on order-keeping assignments elsewhere, exercised their rights before the March 24 poll, as they are scheduled to conduct military missions next Sunday.
A private, who spoke anonymously, insisted that no one -- including his commanders and trainers -- ordered him to vote for a specific candidate.
However, the private said that he encountered difficulties in making a decision because of his limited knowledge of politics.
In fact, he said, he was not aware of the list of candidates that are contesting for a House seat in his constituency.
An army unit chief, who also asked not to be named, admitted that many conscripts from the Northeast rarely keep themselves updated on political affairs, so they tend to follow their families' advice instead of making the decision themselves.
The advance voting took place largely without a hitch, save for some minor problems such as traffic jams, Deputy National Police Chief Srivara Ransibrahmanakul, who is overseeing safety and order during the election, said.
"The congestion on Sunday was caused by the large number of people turning up to vote," he said. "As such, some voters were worried they wouldn't be able to cast their votes by the 5pm deadline."
