THE HAGUE, Netherlands — Former President Rodrigo Duterte is suffering from significant memory loss that prevents him from meaningfully participating in his defense before the International Criminal Court, his lawyers said.

The 81-year-old Duterte faces three counts of crimes against humanity over killings linked to his war on drugs. His trial is scheduled to begin Nov. 30, but ICC judges are first considering whether he is mentally fit to stand trial.

Duterte "suffers from significant memory impairment that prevents him from retaining recent information and reliably accessing memories", according to a defense filing dated 14 September and published Tuesday.

Chief defense lawyer Peter Haynes said the condition prevents Duterte from properly engaging with the case, "let alone give proper instructions to his Lead Counsel, whose name he only sometimes remembers".

The prosecution, however, said Duterte was "capable of meaningfully exercising his procedural and fair trial rights, and that he is fit for trial".

Three medical experts assessed Duterte's condition, but their report has not been made public.

The defense called the assessment "incomplete and inadequate" and sought to cross-examine the experts. It said Duterte at times believed he was living in 2007 or 2008, thought he was 84 or 85 and could not recall the name of the current U.S. president.

Under ICC rules, proceedings cannot continue if an accused is unable to understand the charges or meaningfully participate in a defense.

Duterte is expected to have a pre-trial hearing Wednesday. No public defense request seeking his absence on health grounds had been filed as of Tuesday.