RIYADH/DUBAI (Reuters) - Saudi Arabian authorities have detained 11 princes after they gathered at a royal palace in Riyadh in a rare protest against the government suspending payment of their utility bills, the public prosecutor said on Saturday.

Saudi Arabia, the world’s top oil exporter, has introduced reforms that include reducing energy subsidies, introducing value-added tax and cutting some perks to royal family members to try to cope with a drop in crude prices that has caused a budget deficit estimated at 195 billion riyals ($52 billion) in 2018.

The princes had gathered on Thursday at Qasr al-Hokm palace demanding the cancellation of a recent decree that halted state payment of water and electricity bills for royal family members and seeking compensation for a death sentence implemented in 2016 against one of their cousins, Prince Turki bin Saud al-Kabeer.

“Despite being informed that their demands are not lawful, the 11 princes refused to leave the area, disrupting public peace and order. Members of a security services stepped in to restore order and the princes were arrested,” the public prosecutor’s statement said, without identifying the princes.

“Following their arrest, they have been charged on a number of counts in relation to these offences. They are detained at Al-Hayer prison south of the capital pending their trial.”

News website Sabq earlier identified the leader of the group of princes by the initials S.A.S. The Saud al-Kabeer branch of the House of Saud descend from a cousin of late King Abdulaziz, who founded the modern kingdom.

The meteoric rise of 32-year-old Crown Prince Mohammed bin Salman, the king’s favored son, and his ambitious, sometimes aggressive, policies have caused rare tensions within the royal family, which for decades favored rule by consensus.

Dozens of prices, high officials and senior businessmen were rounded up in November in a crackdown on graft that has boosted Prince Mohammed’s power.

They have been held at the five-star Ritz-Carlton hotel in Riyadh while government officials negotiate financial settlements, asking them to hand over assets and cash in return for their freedom.

The round-up followed a meticulously planned palace coup in June through which Prince Mohammed ousted his elder cousin Prince Mohammed bin Nayef as heir to the throne.