Police Brigadier Ahmed Ali said at the opening of Bashir's corruption trial, which an AFP correspondent attended, that the former president told him that the latest payment was "delivered by some of Mohammed bin Salman's envoys".

Bashir, whose military Islamist regime ruled Sudan for 30 years, arrived at the Judicial and Legal Science Institute where the trial is taking place in a huge military convoy.

Inside the courtroom, he was sitting in a metal cage, unshaven and wearing a white traditional gown.

His relatives in the courtroom chanted "Allahu Akbar" (God is greatest), to which he responded with the same words.

The former strongman was forced from power on April 11 after months of protests. A transitional constitution meant to guide Sudan towards civilian rule was officially signed on Saturday.

Bashir faces a raft of charges of war crimes, crimes against humanity and genocide from the International Criminal Court over his role in the war in Sudan's western Darfur region.

However, the jailed leader appeared in court Monday on charges of receiving and possessing foreign funds illegally.

The police investigator told the court that nearly seven million euros ($7.8 million) were found at Bashir's residence, as well as smaller amounts in US dollars and Sudanese pounds.

"The accused told us that the money was part of a sum of $25 million sent to him by Prince Mohammed bin Salman to be used outside of the state budget," Ahmed Ali said.

The investigator said Bashir had said he also received two previous payments of $35 million and $30 million from Saudi's King Abdullah, who died in 2015.

The investigator said Bashir had said the Saudi money was exchanged and spent and that he could not remember how nor did he have documents providing further details.