State Department spokeswoman Jen Psaki said the purpose of the private meeting was "to express his gratitude for their longstanding and strong relationship."

The sultan has not returned to Oman since traveling overseas for medical tests six months ago for suspected cancer, stirring fears over stability in his Gulf country.

Oman's Sultan Qaboos, who left home for medical tests six months ago for suspected cancer and hasn't returned since, has stirred concerns over stability in his small Gulf country and his eventual succession.

The 74-year-old absolute ruler is not only sultan, but also prime minister, as well as holding the foreign affairs, finance, defense and interior portfolios.

An Iraqi lawmaker has revealed that authorities in Baghdad were seeking to recover around 2 billion dollars of Iraqi money found in a bunker in rural Lebanon.

The MP, who is a member of the parliamentary integrity committee, told the pan-Arab daily al-Hayat published on Friday that the appropriations committee was able to return 1 billion dollars of money frozen in several countries.

Omani authorities have arrested a human rights defender who led Arab spring-inspired protests in the sultanate in 2011, a regional rights group said Friday.

Security forces arrested Saed Jadad Wednesday at his home in the city of Salalah, the Gulf Center for Human Rights said.

U.S. Secretary of State John Kerry met his Omani counterpart Youssef ben Alaoui in London on Wednesday, who is acting as an intermediary in crunch nuclear talks with Iran.

Kerry prolonged his stay in the British capital, where he has been since Monday, and will head to Paris Thursday before flying onto Vienna, where Tehran and six world powers are locked in a final round of negotiations.

Russian Foreign Minister Sergei Lavrov and his U.S. counterpart John Kerry called on Wednesday for an agreement on a nuclear deal with Iran to be reached as soon as possible.

"The need to reach as soon as possible a comprehensive agreement which would allow to fully normalize the situation around the Iranian nuclear program has been acknowledged," the Russian foreign ministry said following a call between Lavrov and Kerry.

U.S. Secretary of State John Kerry arrived Sunday in Oman to seek a breakthrough in nuclear talks with Iran, with domestic pressures weighing heavily on hopes for a deal.

Kerry will meet Iran's Foreign Minister Mohammad Javad Zarif during the day to try to close substantial gaps that have blocked the latest efforts to turn an interim agreement into a comprehensive long-term settlement.

Arab states in the Gulf plan to launch a joint naval force, a top Kuwaiti defense official said on Wednesday, in a bid to protect waters shared with neighboring Iran.

The new force is expected to be formed in the "coming months", Major General Ahmad Yussef al-Mulla was quoted as saying by the official KUNA news agency.

Oman's royal court sought to reassure the nation Thursday about the health of 73-year-old ruler Sultan Qaboos who has been undergoing treatment in Germany for almost three months.

"The sultan is in good health and continuing to follow the medical treatment he has been prescribed and which with the help of God will produce the required results," it said in a statement to mark the Muslim feast of Eid al-Adha that starts on Saturday.

Yemen has freed two Iranians said to be members of the Islamic republic's elite Revolutionary Guards who were accused of links to Shiite rebels, according to sources.

The two men were released on Wednesday thanks to mediation from the neighboring Gulf state of Oman, the Yemeni security and Arab diplomatic sources said.