Saudi Arabia's King Salman on Tuesday ordered the Saudi Arabian National Guard to take part in Riyadh's campaign against Iran-allied Houthi rebels in Yemen, Saudi state media reported.
Military operations in the campaign have so far been carried out by the Royal Saudi Air Force and the Royal Saudi Land Forces, which answer to the Defence Ministry.
The national guard, which is widely regarded as the kingdom's best equipped military ground force, is a separate military structure run by its own ministry.
A number of Arab countries have been contributing to the Saudi-led campaign against the Houthi rebels with air and naval strikes.
The National Guard Ministry is tasked with supporting the armed forces in the defence of national security and the protection of the royal family.
Prince Mutaib bin Abdullah is the current head of the ministry. He was appointed by late King Abdullah in 2013.
The Saudi-led coalition was established after the Houthi rebels captured the southern city of Aden in March.
Arab countries who have joined the coalition include Egypt, Jordan, Kuwait, Bahrain, Qatar, UAE, Sudan, Egypt and Morocco.
Earlier on Tuesday, Iran's deputy foreign minister expressed optimism that a ceasefire in Yemen would be possibly announced soon.
"We are optimistic that in the coming hours, after many efforts, we will see a halt to military attacks in Yemen," Hossein Amir Abdollahian was quoted as saying by Iranian news agencies.
Iran's Foreign Minister Mohammad Javad Zarif called for peace talks between parties to the Yemeni conflict in a phone conversation with UN chief Ban Ki-moon on Thursday.