Rabat (AFP) - Morocco said Sunday it dismantled a "terrorist cell" and seized weapons earmarked for a string of assassinations in a nationwide operation targeting supporters of the Islamic State jihadist group.

The announcement follows last Wednesday's attack on the national museum in the capital of fellow north African state Tunisia, claimed by IS, that killed 20 foreign tourists and a policeman.

The interior ministry said the operation was carried out by a newly formed judicial investigations agency but did not specify the timing or the number of arrests.

Raids were carried out in several cities including Agadir in southwest Morocco, Marrakesh in the south, Boujaad in the centre, Tangiers in the north, Ain Harouda near Casablanca and in the Western Sahara.

"Firearms and a large amount of ammunition" to be used "to assassinate political, military and civilian figures", were seized near Agadir, the ministry said, quoted by the official MAP news agency.

It said members of the dismantled network had pledged allegiance to IS and vowed to target the Moroccan security forces and send recruits to fight in Syria and Iraq.

According to official figures, between 1,500 and 2,000 Moroccans are fighting or have fought alongside jihadists in Iraq and Syria as well as in Libya.