BANGKOK • Thailand's premier yesterday threatened to prosecute anyone who criticised him or his government, as the army detained a former lawmaker for an "attitude adjustment" after he slammed the junta's economic policy.

In a sign the military is not easing its grip on dissent nearly 16 months after seizing power in a coup, former energy minister Pichai Naripthaphan and former Bangkok MP Karun Hosakul - from the ousted Pheu Thai party - are being held for making critical comments over social media.

Reigniting the economy was one of the junta's promises upon its takeover, but what was once one of South-east Asia's most vibrant economies has remained limp.

"This time I will not forgive him if he fails to understand. And if he repeats his actions then he will be prosecuted," Prime Minister Prayut Chan-o-cha told reporters in Bangkok, referring to Mr Pichai.

The former minister, detained for his seventh "attitude adjustment" session since the coup, had criticised the ruling junta's economic plans on Facebook, suggesting his own ideas for reviving Thailand's faltering economy.

Since the May 2014 coup, scores of people have been required to attend such sessions, which are effectively a brief period of involuntary incarceration by the military that can last up to seven days.

General Prayut, who is known for his mercurial outbursts, also warned critics against insulting him or the government. "All those who cause divisiveness or make groundless accusations against the government will face charges of inciting unrest and prosecution," he said. "Anyone involved in past mistakes should not speak out. Don't oppose me," he said.

On Thursday, Mr Karun was detained for "criticising the government unconstructively", Gen Prayut said, but he did not elaborate on the content of the criticism.

AGENCE FRANCE-PRESSE