BANGKOK (AFP) - The political party toppled in Thailand's 2014 coup urged voters Wednesday (March 30) to reject the military's proposed new constitution, describing it as an undemocratic document that would further entrench army rule.

A panel appointed by the ruling military junta unveiled its draft constitution on Tuesday, touting it as the solution to the kingdom's decade-long political crisis.

But critics lambasted it as divisive and a throwback to the days when Thailand's legislature was weak and controlled by unelected people.

In a statement the Puea Thai Party told supporters to vote against the charter during a planned referendum on Aug 7.

"(The party) will not accept a charter in which real power does not belong to the people," Puea Thai said in the statement, putting it on a collision course with the generals.

The junta has warned it will not tolerate criticism of the charter in the run-up to the vote, making debate all but impossible.

Two opposition politicians were detained by the military this week for voicing criticism of the document and of the junta.

The Puea Thai administration of then-Prime Minister Yingluck Shinawatra was dumped from office in a May 2014 coup that brought army chief Prayut Chan-O-Cha to power. He has clamped down on dissent with an iron fist.

Parties loyal to Yingluck and her billionaire brother Thaksin, who was toppled as premier in a 2006 coup, have swept the last three elections. But they are loathed by the Bangkok elite who are determined to see them never return to power.

If the charter is ratified, it will perpetuate the military's influence.

A junta-appointed senate would check the powers of lawmakers for a five-year transitional period following fresh elections.

The document also enshrines a proportional voting system, a move that would likely reduce the majority held by any elected government once Thais regain the right to vote.

The drafters insist their new constitution - the kingdom's 20th in less than a century - will end the cycle of elections, street protests and coups by checking the power of notoriously fractious elected politicians.

But critics say it is aimed squarely at breaking the Shinawatras' electoral stranglehold on the country and maintaining the military's power at a time of deep uncertainty - with the health of revered 88-year-old King Bhumibol Adulyadej failing.

The prospect of the constitution passing the referendum will likely depend on how Puea Thai's political opponents, particularly the Democrat Party, tell people to vote.

The Democrat Party, many of whose supporters cheered the coup, has yet to say what it will advise voters. But its leader, former Prime Minister Abhisit Vejjajiva, has publicly criticised the charter.