Oman’s Sultan Qaboos bin Said al-Said will not attend the Camp David summit between the US and GCC leaders on 13 and 14 May.

Instead, Deputy Prime Minister Fahd bin Mahmoud al-Said will head the Omani delegation.

The sultan returned to Oman in late March after spending eight months receiving medical treatment in Germany. Official statements said he was in perfect health and celebrations in Oman were exuberant.

However, Sultan Qaboos has made just one public appearance since then.

Al-Said will be accompanied by several ministers including veteran Foreign Minister Yousef bin Alawi bin Abdullah.

The GCC leaders are meeting President Barack Obama to discuss regional security issues, especially those in Yemen, Syria and Iraq.

Oman is particularly affected by the Saudi-led war on neighbouring Yemen. The sultanate has remained neutral, but assisted in evacuating foreign nationals and sending aid.

It is expected to take a mediating role in the crisis, as it has between the US and Iran during nuclear negotiations.

“Oman is not part of that campaign for simple reasons; Oman is a nation of peace,” the sultanate’s foreign minister told news agency Reuters. “We cannot work on peace efforts at the same time we would be part of a military campaign. Those two things do not meet.”

There are concerns that violence could spread over the Yemeni border into Oman’s Dhofar region.

Saudi Arabia’s King Salman bin Abdulaziz al-Saud will also miss the summit.