Sudanese President Omar al-Bashir has decided not to take up an invitation from Saudi Arabia to attend an Islamic summit at which US President Donald Trump will be guest of honour.
Mr Bashir, who cited "private reasons", is wanted for alleged war crimes in Darfur and the US was reportedly unhappy about his attendance.
Sudan had said it was looking forward to improving US ties at the event.
Saudi Arabia is the first stop on Mr Trump’s first foreign tour.
A statement from Mr Bashir’s office said the president had apologised to King Salman of Saudi Arabia for being unable to attend the Riyadh summit. No further explanation was given.
Minister of State Taha al-Hussein will represent him.
In 2009 and 2010, the International Criminal Court issued arrest warrants against Mr Bashir for genocide, war crimes, and crimes against humanity related to the conflict in Darfur, which has claimed at least 300,000 lives.
He denies the charges, and has successfully evaded arrest for several years.
Saudi Arabia is not a signatory to the statute that founded the ICC and neither Sudan nor the US have ratified it.
But a US official told NBC News earlier that the Trump administration opposed invitations or travel by individuals facing ICC indictments.
"While the United States is not a party to the Rome Statute... we nevertheless strongly support efforts to hold accountable those responsible for genocide, crimes against humanity and war crimes," the official said.
The Saudi summit brings together more than 50 leaders from Arab and Muslim nations.
Mr Trump will deliver a speech on his "hopes for a peaceful vision of Islam".
His trip will also take him to Israel, the West Bank and Europe.