DUBAI — Three Saudi brothers have been arrested in connection with the suicide bombing of a Shiite mosque in Kuwait last month, the Saudi and Kuwaiti authorities said Tuesday.

The attack on June 26 during Friday Prayer killed 26 people, plus the bomber, and was Kuwait’s deadliest militant attack. Two of the suspects, Majed and Mohammed al-Zahrani, transported the explosives across the border into Kuwait in an ice cooler the day before the attack, Kuwait’s Interior Ministry said, passing them on to another man.

Majed was arrested in the western Saudi city of Taif, while Mohammed was taken into custody after a shootout at a house near the Kuwaiti border in which two police officers were wounded. A third brother, whom the ministries did not identify and whose precise role was not described, was arrested in Kuwait and extradited to Saudi Arabia.

The three were “parties to the crime of the sinful terrorist bombing that targeted the Imam al-Sadeq mosque in Kuwait,” the SPA state news agency quoted a spokesman for the Saudi Interior Ministry as saying.