BANGKOK (AFP) - The firebrand leader of anti-government protests that presaged Thailand's 2014 military coup was indicted on treason and terrorism charges on Wednesday (Jan 24) linked to the deadly demonstrations.

Suthep Thaugsuban, whose protest movement paralysed Bangkok for months and led to the toppling of the elected government in May 2014, was formally charged alongside eight other Democrat party politicians.

The protests against former premier Yingluck Shinawatra were marred by violence that left 28 dead, generating unrest the army said warranted its power grab - the 12th successful takeover since 1932.

Suthep, a former deputy prime minister and nemesis of the billionaire Shinawatra clan, gave barnstorming speeches across Bangkok, leading daily marches in a self-proclaimed "shutdown" of one of South-east Asia's largest cities which lasted for weeks while armed guards patrolled protest sites.

The military dispersed the rallies after toppling Yingluck and has run the country ever since.

Suthep and eight other Democrat politicians - a faction seen as aligned with the army - were charged with "treason, illegal gathering, and incitement," said the state prosecutor's deputy spokesman Prayut Petkhun.

Suthep and Chumpon Julsai, a former Democrat MP, were also charged with terrorism, he told reporters.

The case comes as the kingdom's rancorous political scene - which has been dormant since the coup - stirs back to life ahead of elections slated for late 2018, but whose timeframe keeps slipping.

The junta has yet to lift its ban on politics, making it difficult to track shifting alliances among the kingdom's power brokers.

But the treason and terrorism case could end any lingering political aspirations held by Suthep.

The Shinawatras' ousted Pheu Thai party has also been severely weakened since the coup, with former premier Yingluck fleeing the kingdom last year to avoid a corruption conviction she says was politically motivated.

Analysts say that leaves the military set to extend its influence long after the poll.

Rumours are rife that a potential junta-backed party may run in the elections.

A new charter has already shrunk the power of elected politicians and reserves several parliament seats for military leaders.