JAKARTA (AFP) - Sword-wielding militants killed an Indonesian policeman and critically injured another on Monday (June 1) in what authorities described as a terror attack by suspected ISIS-linked militants.

One of the militants was shot during the early morning raid at a police post in South Daha district in South Kalimantan on Borneo island, authorities said.

"The suspect died on the way to the hospital, while the police officer died at the scene," National Police spokesman Ahmad Ramadhan told Agence France-Presse, adding that authorities were probing possible links to the Islamic State in Iraq and Syria group.

Authorities said they confiscated a samurai sword brandished by one attacker, a koran and a letter calling for jihad.

A flag bearing the tauhid - which expresses the belief in Allah as the one and only god - was also found, they added.

Indonesia, the world's most populous Muslim-majority nation, has long struggled with Islamist militancy and is home to dozens of radical groups that have pledged loyalty to ISIS's violent ideology.

Monday's violence happened on a public holiday that celebrates the South-east Asian archipelago's pluralist democracy, and many past attacks have been against police and other state symbols.

In April, a couple with links to ISIS went on trial for a failed assassination attempt on Indonesia's former chief security minister last year.

The pair were allegedly members Jamaah Ansharut Daulah (JAD), an ISIS-linked extremist group responsible for a string of attacks, including suicide bombings at churches in Indonesia's second-biggest city Surabaya in 2018 that killed a dozen people.

Last November, an ISIS-linked suicide bomber killed himself and wounded six others in a police station attack on Sumatra island.