Interior ministers of the Gulf states Friday vowed to take a united stand against a string of deadly bombings targeting Shiite mosques claimed by the Islamic State jihadist group.

Holding an emergency meeting in Kuwait, the scene of the latest suicide attack that killed 26 people last Friday, the ministers of the Gulf Cooperation Council (GCC) states stressed the attacks are a threat to the stability of the region.

Washington has transferred six inmates from its Guantanamo Bay prison to Oman, the Pentagon said Saturday, as part of a drive by President Barack Obama to close the controversial jail.

"The United States is grateful to the government of Oman for its humanitarian gesture and willingness to support ongoing U.S. efforts to close the Guantanamo Bay detention facility," a statement said.

An American among several believed held by Huthis in Yemen was freed and receiving treatment Tuesday in neighboring Oman, which has been hosting talks between Washington and the Iran-backed Shiite rebels.

A diplomat in Muscat said the talks between the Americans and the Huthis were aimed at promoting a proposed peace conference in Geneva, which the United Nations has so far failed to persuade the warring parties to attend.

An American among several believed held by Huthi Shiites in war-ravaged Yemen was Monday freed and flown to neighboring Oman, host of talks between the US and the Iran-backed rebels.

A diplomat in Oman said the talks between the Americans and the Huthis were aimed at promoting peace negotiations, which the U.N. has so far failed to organize in Geneva.

Oman is hosting unprecedented talks between delegations from the U.S. and Yemen's Shiite rebels aimed at finding a solution to the Yemen war, a Yemeni government spokesman said Sunday.

"The discussions between the Huthi (rebels) and the American delegation are being held at the request of the Americans," said Rajah Badi, spokesman of the Yemeni government exiled in Saudi Arabia.

Iran's foreign minister held talks in neutral Oman Tuesday about ending the conflict in Yemen where a Saudi-led coalition is waging a bombing campaign against Tehran-backed rebels, Iranian media reported.

Oman, which maintains good relations with Iran, is the only one of the six Gulf Arab states that has not joined the coalition air war in its western neighbor.

U.S. Secretary of State John Kerry met Gulf foreign ministers in Paris on Friday ahead of a summit in which President Barack Obama will seek to reassure the Arab monarchies over his Iran policy.

Fresh from a trip to Riyadh where he urged a ceasefire in Yemen, Kerry met foreign ministers from the six members of the Gulf Cooperation Council: Qatar, Kuwait, Bahrain, Oman, the United Arab Emirates and Saudi Arabia.

Human Rights Watch criticized Oman Tuesday for refusing to grant a rights activist bail pending an appeal of his conviction using the Internet to sow unrest in the normally stable sultanate.

Blogger Saeed Jaddad, 48, was jailed this month for three years on charges of undermining the status and prestige of the state, inciting rallies via social media ahead of the anniversary of February 2011 protests and calling for what could undermine public order.

An Omani court has jailed a rights activist for three years after convicting him of sowing unrest in the normally stable sultanate through social media networks, a rights group said Monday.

The court of first instance in Muscat sentenced on Sunday Saeed Jaddad in three cases, the Monitor of Human Rights in Oman organization said.

Amnesty International warned Monday of the "seriously" deteriorating health condition of a detained Omani human rights defender on hunger strike since his January 21 arrest in the city of Salalah.

Saeed Jaddad, who led Arab Spring-inspired protests in the sultanate in 2011, was hospitalize on January 23, two days after he started a hunger strike following his arrest.