Thailand's junta has formally begun cracking down on the internet after television channels were ordered off the air except to carry the army's announcements.

The National Peace and Order Maintaining Council (NPOMC), which is presently running the southeast Asian nation, has told the country's internet service providers [ISPs] to block all content in cyberspace which is seen as violating coup orders.

Officials from the council, which is led by General Prayuth Chan-ocha, held talks with representatives of various ISPs earlier in the day.

Live television broadcasts and access to IPTV have also been ordered to be blocked, a source told the Nation.

Morragot Kulatumyotin, managing director of leading internet provider INET, said general online communications are not affected. However, anything that is against the junta is banned.

"INET would like to tell the people to use the internet normally, but they should avoid forwarding messages that they are not sure about their fact," said Morragot.

Meanwhile, Prayuth told high-ranking military authorities during a meeting that the coup was necessary to resolve the months-long political crisis.

He said he had to make "sacrifices" in order to take over power to safeguard national interests.

Security has been beefed up at border crossings and scores of political figures have been ordered to remain inside the country.

The Pheu Thai Party, which was in power, is reportedly awaiting orders from former prime minister Thaksin Shinawatra to deal with the situation.

For the past six months, Thailand has been grappling with severe anti-government protests that forced then prime minister Yingluck Shinawatra to dissolve parliament and call for fresh elections on 2 February.

The anti-government protests were originally set off by a controversial amnesty bill which might have allowed Yingluck's brother and former leader Thaksin to return from his self-imposed exile.

Thaksin was overthrown in a military coup in 2006 and Yingluck was accused of running the government as his proxy.