Tongan police are considering laying treason charges against people insulting the royal family on Facebook, says the kingdom's attorney general.

It comes as the government mulls blocking the social media platform because of escalating tensions between pro-democracy groups and supporters of the monarchy over a set of contentious bills which would weaken the King's powers while strengthening the government's.

A working group is expected to reach a conclusion on how to respond to the Facebook abuse in the coming weeks. The attorney general, Linda Folaumoetu'i, presented an advisory paper to cabinet on Friday.

Still, even as the multi-agency effort considers several options, including the Facebook ban, police are already investigating Facebook pages involved, said Ms Folaumoetu'i.

"There's a couple of accounts with Tongan names that have actually shown pictures and comments which may amount to defamation or sedition or treason," she said, adding that the prime minister and government had also been targeted by some Facebook pages.

(L to R) Tonga's Queen Nanasipau'u and her husband King Tupou VI. Photo: RNZ

Ms Folaumoetu'i said police had already struggled to identify who was behind the pages - and whether they were even based in Tonga - and were worried any arrests could "create security issues".

"At the moment there's a lot of tension between pro-democracy people, groups, and those who support the king."

Observers say both sides have mobilised thousands of mostly anonymous Facebook accounts to launch attacks on opponents and push political messaging.

"These conversations through Facebook, it's just adding fuel to extreme groups within the country," said Ms Folaumoetu'i.

- By RNZ