The emir of Kuwait said on Thursday his country had thwarted attempts to sow sectarian divisions after last month's suicide bombing but warned that the world needs to do more to confront the "satanic" behaviour of Islamist militants.

An Islamic State suicide bomber blew himself up inside a Shi'ite mosque in the Western-allied Gulf Arab state on June 26, killing 27 people in the worst militant attack in a decade.

Kuwaiti officials say the bombing appeared aimed at stoking sectarian hatred between Sunni and Shi'ite Muslims in the country. Three Saudi brothers who helped the bomber, who entered the country from Saudi Arabia hours before the attack, have been arrested, Kuwaiti and Saudi authorities said on Tuesday.

"You have foiled the desperate attempt and satanic attitudes of the plotters and perpetrators of this condemned crime to inflame divisions and stir sectarian tensions and divide the unity of the Kuwaiti society," Sheikh Sabah al-Ahmed al-Sabah told Kuwaitis in a Ramadan message aired on state television.

"The international community should exert all their effort to avert and take legal action to dry up from its waters so countries and nations live in peace and security."

Up to 30 per cent of Kuwait's 1.4 million citizens are Shi'ite Muslims, who have enjoyed relatively good relations with the country's majority Sunnis. The Gulf Arab state however sits on a fault line and shares its borders with Iraq and Saudi Arabia in a region that has been swept with sectarianism.

Islamic State, whose Sunni jihadist forces have seized large tracts of eastern Syria and northern Iraq, views Shi'ites as heretics and wants to expel them from the Arabian Peninsula, including Kuwait.

"We believe that Kuwait is for all its citizens and not for one party or sect," Sheikh Sabah said. "All live on its earth and ally themselves to its identity.

"We need to remember that our country has stable democratic roots that are inherited by the Kuwaiti people. Everybody has the right of speech and we are proud of our legislation that we agreed on. It's our pride," he added.

The bombing was the most lethal in any of the six hereditary-ruled Gulf Arab states since a campaign of al Qaeda bombings was stamped out in Saudi Arabia a decade ago. - Reuters