NAIROBI, Kenya (AP) — Kenyan police have arrested two Kenyans who were deported from Turkey on suspicion of training with the Islamic State organization in neighboring Syria, officials said Saturday.

Philip Tuimur, the regional police boss for Kenya's coastal region, said the man and woman were under investigation for joining a banned group, which is a criminal offense. They were arrested in the coastal city of Mombasa.

Kenya has been struggling to contain the recruitment of youth by extremist groups, particularly in its coastal region with its Muslim-majority population and high unemployment. Authorities fear that the Islamic State group is trying to establish a presence in East Africa's biggest economy and telecommunications and transport hub.

Dozens of young Kenyans have travelled to Syria and Libya to join the extremist group, according to police.

A senior police source who insisted on anonymity because the source was not authorized to discuss the latest case said the two Kenyans were arrested by Turkish authorities while entering from Syria in November after going for training with the IS group.

Last year, three women in their 20s assaulted a Kenyan police station on the anniversary of the September 11, 2001, attacks in the United States after pledging allegiance to the Islamic State, according to Kenyan authorities.

In a separate case, four medics face extremism-related charges after being accused of plotting an anthrax attack under the supervision of Islamic State handlers.

Al-Qaida has long had a presence in Kenya through its affiliation with the Somalia-based extremist group al-Shabab, which has carried out deadly attacks inside Kenya while claiming retaliation for Kenyan military involvement in combating the extremist group.

Hundreds of Kenyan youth make up al-Shabab's largest contingent of foreign fighters.