Riyadh, May 24 (IANS): Saudi Arabia has said that the suicide bomber at the mosque attack killing 21 worshipers was a Saudi national and a member of Islamic State (IS), Saudi Press Agency reported.

The Interior Ministry said in a statement on Saturday that Saudi bomber Saleh bin Abdulrahamn Al Qashami was a fugitive when he was a member in an terrorist cell under IS.

The cell was discovered this month and 26 Saudi members were arrested.

The ministry said that five members of the cell were involved in shooting at a Saudi soldier in the west Riyadh this month.

The ministry added that the security forces continue to investigate the two cases to identify other suspects, adding that terror attack against worshiping places and worshipers were carried out through foreign plots to promote disunity and sedition in the country.

On Friday, a suicide attack that targeted "Imam Ali" Mosque in Qudaih area of the Saudi city of Qatif killed at least 21 worshipers and injured 101.

The mosque belongs to the minority Shiite community in the country that with high population of conservative Sunni citizens.

The IS shortly claimed responsibility for this attack, saying that "the soldiers of the Caliphate" were behind the blast.

Saudi security authorities have been involved in a war against internal terror and extremism. Terror cells linked to the IS have been recently dismantled.