Indonesian police say four foreigners arrested on Saturday planned to join one of Indonesia's most wanted terrorist leaders.

The four men from Turkey were arrested by Indonesian police and the anti-terrorism squad Detachment 88 on Saturday.

They are reportedly being investigated for links to Islamic State militants in Iraq and had planned to join up with Santoso, a wanted Indonesian terrorist cell leader.

Santoso is understood to have been the field commander of Jemaah Ansharut Tauhid (JAT), an offshoot of Jemaah Islamiah, an Al Qaeda-linked cell which was behind the Bali bombings.

Indonesia's national police spokesman, Boy Rafli, says another wanted man called Mochtar, from the terrorist stronghold of Poso, had organised for the Turkish men to meet up with Santoso.

Indonesia is home to the world's biggest Muslim population of about 225 million and has long struggled with terrorism.

But a successful clampdown in recent years has seen the end of major deadly attacks.

Jakarta has estimated that dozens of Indonesians have travelled to Syria and Iraq to fight and president Susilo Bambang Yudhoyono said he was concerned about their return, adding that he had tasked agencies to oppose the spread of extremist ideology in the sprawling nation.

ABC/AFP