Saudi officials say 12 out of 19 people arrested over Monday’s three bomb attacks in the country are Pakistani.
An interior ministry spokesman also named a suicide bomber who killed four security officers near a mosque in the sacred city of Medina as Near Muslim Hamad, a 26-year-old Saudi man.
The ministry said he had a history of drug abuse.
Three people who allegedly carried out attacks in Qatif were also named and identified as Saudi nationals.
Their names were given as Abdulrahman al-Omar (23), Ibrahim al-Omar (20) and Abdulkarim al-Husni (20). The ministry said none of them had Saudi IDs.
The attacks in Qatif took place on the same day and were also suicide bombings.
A man died in Jeddah on Monday when attempting to detonate a bomb.
No group has claimed responsibility for the attack in Medina, or for two other suicide bombings the same day outside a Shia mosque in the eastern city of Qatif and near the US consulate in Jeddah. However, they are suspected to have been the work of people with allegiances to so-called Islamic State.
The group has previously targeted Saudi security personnel and Shia mosques.
Saudi King vows iron fist
Saudi Arabia’s King Salman bin Abdulaziz Al Saud has vowed that his government will “strike with an iron fist”, a day after suicide bombers struck three cities in an apparently coordinated campaign of attacks.
In a speech marking Eid al-Fitr, the holiday that celebrates the end of the Islamic holy month of Ramadan, King Salman said a major challenge facing Saudi Arabia was preserving hope for youth who faced the risk of radicalization.
“The kingdom is fully determined to strike with an iron fist all those who aim at the minds or ideas of our dear young people,” Salman said on Tuesday, in an address to the nation for the Islamic feast of Eid al-Fitr.
Four security guards were killed on Monday outside the Prophet’s Mosque in Medina, Islam’s second holiest site, as suicide attackers also struck two other cities.
US consolate in Jeddah and Shiite mosque in al-Qatif were targeted by suicide attacks.
Following the attack, Mohammed bin Nayef bin Abdul-Aziz, Saudi’s crown prince who is spearheading the country’s anti-terror efforts, visited wounded victims, as he sought to reassure Saudis that the country’s security “is at its highest levels”.
“I know confronting terror operations is not simple. The simple repercussions you feel following the explosion will go away. I’ve been through this experience before and I [understand] how you feel,” Al Arabiya TV quoted him as saying.
