Iraqi forces on Tuesday battled up to the edge of Al-Qaim, the largest town still held by the Islamic State group in the country, as they pushed a final assault on the jihadists.
The man, identified only as Yamen A., 19, was held at dawn by special forces in the northeastern town of Schwerin, the federal prosecutor's office said in a statement.
Philippine troops on Tuesday killed a pro-Islamic State gunman in the southern city of Marawi, a military official said, eight days after the government declared the end of hostilities.
Former residents and the Syrian Observatory for Human Rights said there were heavy aerial strikes on eastern Syria's largest city as troops pushed towards the Hay al Umal area.
The separate assaults across the Iraqi-Syrian frontier aim to deal a final blow to the Islamic State "caliphate" that has crumbled this year in Syria and Iraq.
Iraqi troops launched an assault on the last Islamic State group bastion in the country on Thursday even as the Kurds said Baghdad's forces had attacked their fighters near the border with Turkey.
Two soldiers were killed and three wounded at a military checkpoint in northeastern Libya on Wednesday, witnesses and officials said, in an attack claimed by Islamic State.
Indonesian authorities arrested nine men suspected of having links to a militant network loyal to Islamic State and planning a series of attacks on police posts, said a police spokesman.