Saudi Arabia’s King Salman bin Abdulaziz al-Saud has taken away key powers from the kingdom’s Interior Ministry as part of an overhaul of the country’s security agencies just a month after his son became heir to the throne, displacing the monarch’s nephew and long-time interior minister.

The king has established a homeland security agency called the Presidency of State Security, which will report to the prime minister, a title the king himself holds, according to royal decrees published by the official Saudi Press Agency (SPA).

Some of the departments handled by the Interior Ministry – including investigations, special security forces, emergency forces, aviation security, the general directorate of forensics, the national information centre and others in charge of combating terrorism and its financing – will be moved to the new security agency.

“Whatever concerns the security of the state, including civil and military personnel, budgets, documents, and information will also be transferred to the new authority,” the royal decree stated, adding that the necessary review of laws and regulations will follow.

The royal orders consolidate the king’s control over security services in the kingdom, which has been a key player in the fight against terrorism. The security overhaul follows the palace shake-up last month. The king relieved Crown Prince Mohammed bin Nayef al-Saud and appointed his 31-year-old son, Prince Mohammed bin Salman al-Saud, in his place.

The royal order suggested the restructuring was first proposed by Prince Mohammed bin Nayef. The move aims to help security agencies face challenges “with a great degree of flexibility and readiness”, according to the SPA report.

The Interior Ministry has been the main agency responsible for controlling Al-Qaeda and Islamic State in Iraq and Syria (Isis) insurgency in the kingdom.

The decision to reorganise the security agencies aims at refocusing the Interior Ministry on domestic issues such as traffic laws, immigration and airport security, while the security issues will be handled by the new agency. The changes are part of long-term reforms to overhaul the Saudi economy and government, media reports have cited unnamed Saudi officials as saying.