A senior Saudi prince and grandson of the state's founder has issued an unprecedented call for change in the country's leadership, the Guardian reported on Monday.

The prince, who was not named for security reasons, wrote two letters to members of the sprawling royal family earlier this month calling for the removal of the current leader, King Salman, who ascended to the throne in January this year.

The prince reportedly told the Guardian that the king is not in good health and that recent events in the kingdom have led to disquiet in the royal family, as well as among the wider public.

“The king is not in a stable condition and in reality the son of the king [Mohammed bin Salman] is ruling the kingdom,” the prince is quoted as saying.

He added that he expected four or five of his uncles, Salman's brothers and half-brothers, to meet shortly and discuss the issues he raised in his letters.

"They are making a plan with a lot of nephews and that will open the door," he said. "A lot of the second generation is very anxious.”

“The public are also pushing this very hard, all kinds of people, tribal leaders,” the prince added. “They say you have to do this or the country will go to disaster.”

The kingdom has been buffeted by a series of setbacks recently: The precipitous drop in the price of oil, Saudi Arabia's key export, a draining war against Shi'ite rebels in neighboring Yemen and, most recently, two disasters during the recent hajj in Mecca that left over 800 people dead.

Blame for country's slow and hesitant response to the hajj deaths and its halting efforts to deal with the other challenges is being laid at the door of King Salman, his crown prince, Mohammed bin Nayef, and the deputy crown prince, Mohammed bin Salman, Salman's son.

Prince Mohammed bin Salman, a new arrival to the Saudi senior leadership team, has quickly become one of the most controversial. Although still very young by Saudi standards – officially 35 but rumored to be much younger – he holds a multitude of posts including minister of defense and chair of the Council for Economic and Development Affairs, which is the country’s main economic policymaking committee.

Nicknamed "Reckless," the prince is regarded as being the main proponent of the war in Yemen, which continues to grind on, despite punishing attacks by the Saudi air force and ground forces.

Now, many are accusing Mohammed bin Salman of rushing into the war without a proper military strategy or an exit plan.

The letters from the unnamed prince call on the 13 surviving sons of Ibn Saud – specifically the princes Talal, Turki and Ahmed bin Abdulaziz – to unite and remove the leadership in a palace coup, before choosing a new government from within the royal family.

“Allow the oldest and most capable to take over the affairs of the state, let the new king and crown prince take allegiance from all, and cancel the strange, new rank of second deputy premier,” states the first letter.

“We are calling for the sons of Ibn Saud from the oldest Bandar, to the youngest, Muqrin, to make an urgent meeting with the senior family members to investigate the situation and find out what can be done to save the country, to make changes in the important ranks, to bring in expertise from the ruling family whatever generation they are from.”

The letters are the clearest indication of strife within the royal family since King Faisal deposed King Saud in a palace coup in 1964.