resident Tayyip Erdogan on Sunday dismissed calls for Turkey to close a military base in Qatar and said a wider list of demands issued by four Arab states was an unlawful intervention against the Gulf state's sovereignty.

The chairman of the U.S. Senate Foreign Relations Committee said on Monday he would block arms sales to Saudi Arabia, the United Arab Emirates and other members of the Gulf Cooperation Council pending progress in resolving a simmering dispute with Qatar.

A boycott imposed by four Arab nations that accuse Qatar of supporting terrorism is squeezing the tourism sector and Doha's hotels which would normally be full in the Eid al-Fitr holiday have seen steep falls in their occupancy rates.

Iranian Foreign Minister Mohammad Javad Zarif called on Monday for Europe to use its influence to defuse tensions in the Gulf where Saudi Arabia and its allies have cut ties with Qatar.

Iranian President Hassan Rouhani voiced support on Sunday for Qatar in its confrontation with Iran's rival Saudi Arabia and its allies, saying a "siege of Qatar is unacceptable", the state news agency IRNA reported.

Iranian authorities have rounded up at least 50 people suspected of links to militant groups in a Western province, a prosecutor said on Sunday, the latest in a wave of arrests following twin bomb and gun attacks in Tehran in early June.

U.S. Secretary of State Rex Tillerson said on Sunday that Qatar and the four Arab states that imposed a boycott on their tiny but wealthy neighbor should sit down together in order to try to reach a resolution.

The cost of insuring exposure to Qatari sovereign debt rose to a one-year high on Monday after neighbouring Arab states, which have imposed sanctions on Qatar, issued an ultimatum, giving Doha 10 days to comply.

The president of the United Arab Emirates (UAE), Sheikh Khalifa bin Zayed al-Nahyan, made a rare public appearance on Sunday since suffering a stroke in 2014, state news agency WAM said, receiving well-wishers for the Muslim Eid al-Fitr feast.

A list of 13 demands submitted by four Arab states to Qatar as a condition to lift their boycott on the Gulf country is "very provocative" because some items challenge Doha's sovereignty, German Foreign Minister Sigmar Gabriel said on Monday.

Eight Emirati princesses were convicted of human trafficking by a Belgian court on Friday and were given suspended jail terms and fines in a case stemming from their treatment of servants.

Saudi security forces on Friday foiled a suicide attack on the Grand Mosque in the Muslim holy city of Mecca, cornering the would-be attacker in an apartment, where he blew himself up.

A Qatar semi-government human rights body said on Saturday that a list of demands, presented to Qatar by four Arab states imposing a boycott on the wealthy Gulf country, were a violation of human rights conventions.

Qatar is reviewing a list of demands presented by four Arab states imposing a boycott on the wealthy Gulf country, but said on Saturday the list was not reasonable or actionable.

The United Nations aviation agency will hold a special hearing next Friday on Qatar's request to reopen Gulf airspace that was closed to its flights during a major diplomatic dispute with other Arab powers, its transport minister said on Friday.

If Islamic State leader Abu Bakr al-Baghdadi is confirmed dead, he is likely to be succeeded by one of his top two lieutenants, both of whom were Iraqi army officers under late dictator Saddam Hussein.

Saudi Arabian police foiled a "terrorist action" against Islam's holiest site on Friday, where millions of faithful from around the world have gathered, the state Al-Ekhbaria news channel said.

Turkey rejected a call from four Arab states on Friday to shut down its military base in Qatar, saying the base was a guarantor of security in the Gulf and demands for its closure represented interference in its ties with Doha.

The elevation of Mohammed bin Salman as Crown Prince of Saudi Arabia has ended two years of speculation about a behind-the-scenes rivalry near the pinnacle of royal power, but he still has to win over powerful relatives, clerics and tribesmen.

Four Arab states boycotting Qatar over alleged support for terrorism have sent Doha a list of 13 demands including closing Al Jazeera television and reducing ties to Iran, an official of one of the four countries said.