A rule introduced in 2012 requires major events like the football World Cup, SEA Games and Olympics to be aired free. Others like the English Premier League are available via subscription-based TV channels.

Live coverage of the Olympics in Rio will be rotated among five television channels in Thailand this year amid controversy.

The network, which reportedly paid 450 million baht (S$17.4 million) for the broadcasting rights, had requested a 150 million baht government subsidy.

Word of the proposal ignited criticism that public money was being used to benefit certain large TV stations at the expense of other players in Thailand's broadcast industry, which comprises more than 24 free-to-air digital channels.

A commissioner from the National Broadcasting and Telecommunications Commission (NBTC), Thawatchai Jittrapanun, told The Straits Times the issue was still in limbo. "It's not fair for competition," he said.

The five TV channels broadcasting this year's Olympics are established players in the market. They are private channels 3 and 7, state majority-owned 9, the Thai army-run channel 5 and the government-run National Broadcasting Services of Thailand (NBT). They form a network called the TV Pool.

Altogether, sport fans would be able to catch 200 hours of live broadcasts.

But the TV Pool is reportedly having trouble selling commercials for its Olympic broadcasts. As at late last month, it had managed to fill only 20 per cent of available advertising air time.

This is not the first time that broadcasts of live sports events have ignited debate.

A 2012 rule requires major sports events to be aired for free. But RS, a Thai media company, bought the rights to the 2014 Fifa World Cup before the rule was introduced.

In 2014, despite a court ruling that upheld RS' rights over the World Cup matches, the then-newly installed military government pressed the NBTC to make the company rethink its position.

The NBTC reached a last-minute deal to pay 427 million baht to RS - just over half of what RS had expected to make for the event - to air all the matches on free-to-air TV. The matches were aired on channels 5 and 7, as well as RS' own digital channel.