In a statement on the official KUNA news agency, the ministry said that 202 people were wounded in the unprecedented attack.
The IS-affiliated group in Saudi Arabia, calling itself Najd Province, said militant Abu Suleiman al-Muwahhid carried out the attack on the mosque, which it claimed was spreading Shiite teachings among Sunni Muslims.
The blast hit Al-Imam al-Sadeq mosque in Kuwait City, the interior ministry said in a brief statement without providing details.
The television showed footage of massive destruction caused by the blast, and people posted online horrific pictures of the dead and wounded.
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The Kuwaiti cabinet went into an emergency meeting to discuss the incident, as the interior ministry raised the level of alert and mobilised all security forces.
A number of hospitals in the oil-rich emirate declared states of emergency to deal with the wounded, while the central blood bank appealed for blood donations.
Kuwaiti Shiites make up around one-third of the country's native population of 1.3 million people.