Monday’s Medina attack, which killed four policemen, followed suicide bombings in Jeddah and eastern city of Qatif.
Saudi Arabia has arrested 46 people suspected of belonging to a cell responsible for an attack in Medina outside of one of Islam’s holiest sites last year.
“Investigations revealed they were directly involved in the crime of targeting worshippers in the Prophet’s sacred mosque,” Interior Ministry spokesman Major-General Mansour al-Turki told reporters on Sunday.
Turki said the group was also behind a suicide bombing near the US consulate in Jeddah in 2016. Both attacks took place in July during the final days of the Muslim holy month of Ramadan.
The bombing outside Prophet Muhammad’s mosque in the western Saudi city of Medina killed four security officers, while two policemen were wounded in the attack in Jeddah.
The ministry previously identified the Medina bomber as a Saudi national and the Jeddah bomber as a Pakistani.
There was no claim of responsibility for the attacks, nor did the Interior Ministry blame a specific group.
In recent months, Saudi authorities have stepped up a nationwide clampdown on suspected attackers.
Islamic State of Iraq and the Levant (ISIL), based in Iraq and Syria, has carried out a series of bombings and shootings in Saudi Arabia since mid-2014 killing scores of people, mostly members of the Shia-Muslim minority and security services.