Foreign Minister Julie Bishop has expressed grave concerns about developments in Thailand following confirmation of a military coup, describing the situation on the ground as “volatile”.

Thailand’s army chief on Thursday seized power, declaring a 10pm to 5am curfew, and ordering demonstrators on both sides of the kingdom’s bitter political divide off the streets after seven months of rallies in the capital.

The junta led by army chief General Prayut Chan-O-Cha banned gatherings of more than five people, ordered the ousted cabinet to report to the army and suspended the constitution – except for the section related to the monarchy.

“All Thais must remain calm and government officials must work as normal,” Prayut said in a brief televised address, flanked by four of his top officers.

Ms Bishop says the Australian government is seeking more information about developments in Thailand, and warned Australians travelling to Bangkok to exercise a high degree of caution.

It is a volatile situation. We are monitoring it closely but people need to pay close attention to their personal security and their travel plans.

“We are gravely concerned that the army chief has announced that the military is assuming all government functions in Thailand,” Ms Bishop told ABC radio on Friday.

“It is a volatile situation. We are monitoring it closely but people need to pay close attention to their personal security and their travel plans.”

The Department of Foreign Affairs and Trade has updated its website to reflect the developments and continues to advise travellers to “exercise a high degree of caution” and for people to avoid all demonstrations, protest sites, political events and large-scale public gatherings. 

It’s unknown exactly how many Australians are currently in Thailand, with DFAT only aware of 5000 who have registered with its Smartraveller website.

The announcement of the coup came shortly after the opposing camps and other top political actors had gathered for the second straight day of conciliation talks at a heavily guarded military facility in the capital Bangkok.

It was not immediately clear what happened during the closed-door negotiations between the bitterly divided political foes.

Prayut had ordered participants to bridge their differences for the good of the nation, saying he would not allow Thailand to become another “Ukraine or Egypt.”

“I was concerned with the situation, and could not let it continue without a solution,” Prayut said earlier in opening remarks to the political talks Thursday.

Witnesses saw leaders of Thailand’s two main political parties and its rival protest movements taken away by the military.

It was unclear if they had been formally detained but their whereabouts remained unknown hours later.

The US, EU, France and others expressed deep concern over the developments.

Secretary of State John Kerry urged the restoration of civilian rule, media freedoms and “early elections that reflect the will of the people”, while the Pentagon said it was reviewing military cooperation with its longtime Southeast Asian ally.

UN concern on coup

UN Secretary General Ban Ki-moon is “seriously concerned” over the military coup in Thailand and has called for the rapid return to a democratic civilian government, his spokesman says.

Ban appealed “for a prompt return to constitutional, civilian, democratic rule and an all-inclusive dialogue that will pave the way for long-term peace and prosperity in Thailand”, spokesman Stephane Dujarric said in a statement on Thursday.

“The secretary general urges all parties to work together constructively, refrain from violence and respect human rights,” he added.

The Thai army took power on Thursday and suspended most civil liberties after seven months of unrest and deadly political violence.

History of Thai turmoil

It is the latest twist in a nearly decade-long political crisis stretching back to an earlier coup in 2006 that deposed the controversial tycoon-turned-politician Thaksin Shinawatra as premier – a move that infuriated his supporters.

A Bangkok-based royalist elite and its backers have engaged in several months of escalating confrontation with the democratically elected government aligned to Thaksin.

Thailand’s democratic development has now been interrupted by 19 actual or attempted coups since 1932.

Martial law – declared by Prayut on Tuesday and reaffirmed under the coup – gives the military draconian powers to restrict freedom of assembly and movement and to detain people.

All television and radio stations including foreign broadcasters were ordered to suspend normal programming and broadcast only an army feed.

The junta also said it would block any social media platforms in the country that carry content provoking violence or criticising coup leaders.

Prayut gave no indication how long the military would hold power but said it would “start political reform”, without giving details.

– with AAP