Spanish Prime Minister Pedro Sanchez on Wednesday described corruption charges related to former king Juan Carlos as "disturbing to all", a month after an investigation was launched into the possibility of Carlos receiving a commission from Saudi Arabia in a rail deal.

"There are disturbing allegations that bother everyone, including myself," Sanchez told a news conference with his Italian counterpart, Giuseppe Conte.

"There is media that will not turn a blind eye, and a judiciary that will move about it, and the palace will distance itself."

On June 8, the Supreme Court of Spain opened an investigation into the case of Carlos receiving a commission from the late Saudi King Abdullah bin Abdul Aziz, to conclude a contract worth 6.7 billion euros to construct a high-speed train linking the cities of Makkah and Madinah with a general Spanish alliance 2014.

This news leaked in 2018 when the Swiss newspaper La Tribune de Geneva published it, and said that the commission amounted to $ 100 million and was transferred to the account of the Panamanian Foundation in Switzerland.

Last week, Spanish media released further details of the transfer.

Juan Carlos, 82, has repeatedly refused to respond to these allegations through his lawyer, but his son, the current king Felipe VI, distanced himself from the case and announced that he would abandon his inheritance from his father. He also said that his father would no longer receive his annual allowances in excess of 194,000 euros.

The Spanish monarchs enjoy immunity during their reign, but Juan Carlos no longer enjoys immunity since he abdicated in 2014 in favor of his son, after another corruption scandal involving his daughter Christina and her husband.

Last March, thousands of Spaniards protested on their balcony - in the event of a closure due to an outbreak of the Coruna virus - by clicking on cooking utensils, during a speech addressed to the Spanish people by King Felipe VI, in protest at the scandal related to his father.