Saudi Crown Prince Mohammed bin Salman is using an elite force to suppress dissent within the royal family.

The brigade, which reports directly to the crown prince, is called al-Ajrab Sword (Blood-rusted Sword).

According to Saudi media reports, al-Ajrab Sword Brigade arrested 11 Saudi princes last week after they gathered in the capital Riyadh to protest against newly imposed austerity measures.

The name

The brigade is named after the sword of Imam Turki bin Abdullah Al Saud, the founder of the second Saudi state. Imam Turki is believed to have bestowed this title on his sword after finding rust on its blade.

According to Saudi sources, the sword that appears on the Saudi flag underneath the "tawheed" phrase ("There is no god but Allah") refers to this weapon, which was in Bahrain for more than 150 years before King Hamad bin Isa Al Khalifa gifted it to the late Saudi King Abdullah bin Abdulaziz in 2010.

The makeup

Al-Ajrab Sword Brigade is an elite force formed after Salman bin Abdulaziz became king of Saudi Arabia in January 2015.

The brigade comprises more than 5,000 personnel from different military ranks. Selected from forces in the air defence, navy and Royal Guard, they are overseen by Mohammed bin Salman and receive advanced military training including stunts, parachuting, riot control, sniping, combat swimming (frogmen) and explosives.

They are also embedded within the Royal Guard as a special force.

The mission

The nature of the missions assigned to al-Ajrab Sword Brigade is unclear, but activists say its members specialise in sensitive and royal-related cases.

The presidency of the Royal Guard includes branches in all Saudi Arabia's regions. In cooperation with other security sectors, the Royal Guard provides security and protection to the king, crown prince and VIPs inside and outside the country.

One mission that was reportedly assigned to al-Ajrab Sword Brigade was the January 4 mass arrest of the Saudi princes. Saudi media reported that the move came in response to a protest over a government decision to make the country's royalty pay their utility bills.

However, Saudi activists on social media said the rally was an objection to a campaign of arrests targeting royals and the absence of former Crown Prince Mohammed bin Nayef.