Moroccan authorities last month arrested Yassine Abaaoud, a younger brother of the suspected Islamic State mastermind of the Paris attacks, after he arrived in his father¡¯s hometown of Agadir, a Moroccan security source said on Friday.

Abdelhamid Abaaoud, a Belgian militant of Moroccan origin, is believed to have orchestrated last week¡¯s coordinated bombings and shootings that killed 129 people. He was among those later killed in a police raid in a Paris suburb. He was 28.

Yassine was arrested last month after his plane landed in Agadir and has been in custody since, a Moroccan security source, who declined to be named, said. ¡°He has been held for about one month now,¡± the source said.

It was unclear if Abdelhamid¡¯s younger brother has ties with his militant cell in Europe. The source declined to give further details on the arrest.