Moroccan security forces with US support have foiled a suspected bomb plot by the so-called Islamic State group and arrested an alleged supporter of the outlawed organisation, counter-terror police said Friday.

"This arrest is the culmination of close collaboration between (Moroccan security forces) and US law-enforcement," Morocco's Central Bureau of Judicial Investigation (BCIJ) said in a statement without giving further details about the joint operation.

The arrested suspect was "an extremist belonging to the so-called Islamic State", 24, from the Sala Al-Jadida region north of Rabat the statement added.

According to preliminary inquiries the man had allegedly pledged allegiance to the group.

He had planned to join foreign jihadist training camps "before deciding to join a terror plot in Morocco using explosive devices", the statement added. 

The police subsequently seized electronic devices and materials used for the preparation of explosives.

"This security operation highlights the importance and effectiveness of bilateral cooperation between (Moroccan security services) and US intelligence and security agencies in the fight against extremist violence and the threat of international terrorism," the BCIJ said.

Moroccan outlets reported a vast nationwide counter-terror operation on December 8, but official sources did not confirm the crackdown.

On October 6 counter-terrorism police announced the dismantling of a "terror cell" in Tangiers and the arrest of five suspects accused of plotting bomb attacks.

In September a cell affiliated to the Islamic State group was dismantled in south Morocco and seven people arrested.

Since 2002, Moroccan police claim to have dismantled 2,000 "terror cells" and arrested some 3,500 people in cases linked to terror, according to BCIJ data published in February.