A huge arms cache seized in Kuwait last week was smuggled into the country from Iran, two Kuwaiti newspapers reported on Sunday.

The Interior Ministry said on Thursday authorities had found ammunition, explosives, weapons and grenades in holes dug under houses in an area near the Iraqi border. Three men who owned the houses were detained.

Al-Anba newspaper reported at the time that the weapons had been smuggled across the border from Iraq for use by members of an Iranian-backed Hezbollah cell.

But al-Rai and al-Qabas dailies, citing unnamed sources, reported on Sunday that the weapons had been brought into Kuwait by sea from Iran. They quoted the sources as saying that the new information had come from confessions made by the detainees during interrogation.

Al-Qabas said the number of suspects held had risen to 13.

"The suspects have disclosed that there is a direct Iranian line in supplying weapons to Kuwait by sea," al-Rai said.

The Interior Ministry declined to comment.

Another newspaper, al-Jarida, said Iranian Revolutionary Guards had trained members of the cell a year ago, along with citizens from Saudi Arabia and Bahrain, on the use of weapons and explosives, at an unnamed Red Sea island.

It said the trainees had travelled to the island through a port controlled by Yemeni Houthis, an Iranian-linked group which controls much of northern Yemen.

Kuwait, a Western-allied Gulf oil exporter, has been on alert since a suicide bomber killed 27 people in an attack on a Shi'ite Muslim mosque in the capital, Kuwait City, on June 26.

The interior minister said in June it was at war with hardline militants, who officials said were trying to stoke sectarian strife in a state where the two Muslim sects have traditionally coexisted peacefully.

Ties between Iran and its Gulf Arab neighbours are strained by suspicions that Tehran is trying to extend its influence into Arab countries including Syria, Iraq and Yemen. – Reuters