Anonymous hackers attacked more than a dozen Thai police websites in protest against death sentences handed down to two Myanmar migrant workers for allegedly killing two British tourists.
Fourteen Thai police websites were attacked and of those listed nine were inaccessible on Tuesday, according to Anonymous' Facebook page.
Thai police confirmed the cyber-attacks on Tuesday but said there was no confidential data on the public websites.
"They are not good enough to hack into our system and steal any of our data," police spokesman Dechnarong Suthicharnbancha said.
"I received an initial report that the hackers are from another country," Dejnarong said. When asked if he meant they were from Myanmar and whether the hack was in response to the Koh Tao verdict, he said, "It is possible. We are investigating."
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In a 37-minute video posted on the Anonymous Facebook page, a masked person questioned the competency of the Thai police force and its handling of this and other cases.
On December 24, a Thai court found Zaw Lin and Win Zaw Htun, both 22, guilty of killing Hannah Witheridge, 23, and David Miller, 24, whose battered bodies were found on a beach on the southern Thai holiday island of Koh Tao in 2014.
The investigation into the killings drew allegations of police incompetence, torture and mishandling of evidence. A judge dismissed the allegations of torture, saying there was no evidence it took place.
The verdicts sparked anger in Myanmar where hundreds held protests outside the Thai embassy in the commercial capital of Yangon, calling for the two to be released.
The words "Failed Law", "We Want Justice", and a hashtag #BoycottThailand were displayed on some of the hacked sites, along with the name of Myanmar-based "Blink Hacker Group".
Al Jazeera was unable to verify who carried out the attack on the police websites.