BANGKOK (AFP) - Nearly two dozen bomb and arson attacks erupted across Thailand's insurgency-torn south shortly after midnight, the army said Friday (April 7), causing widespread blackouts but no casualties in the Muslim-majority region.

The violence, which saw more than 50 electricity poles toppled by explosives and tires set alight, struck only hours after Thailand's King Maha Vajiralongkorn signed a new military-backed charter into law.

"There are 23 simultaneous incidents in three southern provinces and four districts of Songkhla," said Colonel Pramote Prom-in, an army spokesman for the south.

The border provinces have sizzled with violence for over a decade as ethnic Malay rebels battle Thai troops for more autonomy from the Buddhist-majority state.

The fighting has claimed more than 6,800 lives - mostly civilians - since 2004.

The region was one of few areas to reject the ruling junta's constitution in a referendum that saw the document approved last year.

The new charter curbs the power of elected lawmakers and will bolster the army's role in government even after the junta steps down following elections expected in late 2018.

However Don Pathan, a Thai analyst based in the far south, said Friday's wave of attacks did not appear to be linked to the charter's signing.

The violence was most likely revenge for the killing of two suspected rebels by security forces last month, he told AFP.

"There has been a small spike of violence since then. My gut feeling is that last night was a retaliation for that alleged extrajudicial killing," said Pathan.

The southern region has been hit with a string of suspected rebel assaults since that fatal shooting on March 29, including one that saw around 30 militants open fire on a police checkpoint in Yala province, injuring 12 officers.

The junta, which seized power in 2014, has held several rounds of negotiations with a group that claims to represent the insurgents.

But the talks have failed to make headway and many doubt the rebel negotiators have clout over fighters on the ground.

Speaking to reporters on Friday, defence minister Prawit Wongsuwon blamed the previous night's unrest on a "new generation" of fighters, without elaborating.

The shadowy insurgent movement rarely claims attacks and is believed to have several factions.