Suspected Thai militants shot dead five people, including a nine-year-old boy and a Buddhist monk, in the latest attacks in the kingdom's insurgency-torn deep south, police said Thursday.

The killings appeared to be revenge attacks for the recent deaths of three young Muslim brothers.

Four gunmen on motorcycles opened fire at the monk while he was collecting alms in Mae Lan district of Pattani province on Thursday morning, killing him and three villagers including the boy, police said.

Six other people were wounded, including a policeman providing a security escort for the monk.

On Wednesday evening in Pattani's Yaring district, a 29-year-old Buddhist woman riding a motorcycle home from work was shot dead and her body set on fire, police said.

A note left at the scene said: "To the army chief: this is not the last body for the three brothers."

The brothers -- aged three, five and nine -- were gunned down last week in front of their home in neighbouring Narathiwat province after returning from evening prayers at a mosque.

Their pregnant mother and father were also shot in the attack but survived.

In an earlier act of apparent retaliation, a policeman's wife was shot dead and then set on fire in front of terrified shoppers at a busy market on Monday.

The Muslim-dominated region near the border with Malaysia is in the grip of a decade-long insurgency that has claimed more than 5,900 lives, mostly civilians, in near-daily bomb and gun attacks.

Peace talks between rebels and the government have stalled, with officials blaming a political crisis sparked by months of mass opposition protests in Bangkok seeking to unseat Prime Minister Yingluck Shinawatra.

The insurgents want a level of autonomy from Thailand, which annexed the region over a century ago. They accuse Thai authorities of widespread human rights abuses and disrespecting their religion and culture.