JAKARTA (ASSOCIATED PRESS, REUTERS) - Indonesian police say they have arrested nine suspected militants accused of plotting a suicide bomb attack on police.

National police spokesman Dedi Prasetyo says the counterterrorism squad arrested six people in Jakarta's satellite city of Bekasi on Monday (Sept 23), two others in northern Jakarta and another in western Jakarta.

Reuters reported that the suspects were planning to attack police headquarters in the capital Jakarta.

Mr Prasetyo says the authorities defused a 500g explosive seized from one of the suspects, Muhammad Arshad, when they raided his house.

Police said they also found a goodbye letter written by Arshad, who allegedly planned a suicide attack using the explosive at a police station.

Police said the suspects are believed to be linked to Jemaah Ansharut Daulah (JAD), a local militant network affiliated with the Islamic State group.

Attacks by the Islamic State, also known as the Islamic State in Iraq and Syria, have inspired actions by Indonesian militants despite a sustained crackdown.

The government scrambled to tighten its anti-terrorism laws after a series of suicide bombings linked to JAD cells killed more than 30 people in the city of Surabaya last year.

Hundreds of people have been detained under the new laws since the beginning of 2019.