The International Criminal Court's member countries are set Friday to elect a new chief prosecutor for the war crimes tribunal, a gruelling post whose current holder is under US sanctions.
Four candidates from Britain, Ireland, Italy and Spain are vying to replace Fatou Bensouda, who has led controversial probes into Afghanistan and the Israeli-Palestinian conflict since 2012.
Britain's Karim Khan is said to be in pole position for a nine-year term as prosecutor ahead of Carlos Castresana of Spain, Ireland's Fergal Gaynor and Italy's Francesco Lo Voi, according to British media reports.
The ICC's member states have failed to reach a consensus despite several attempts in recent weeks, and will now vote on the new prosecutor at the United Nations in New York.
Gambian-born Bensouda is due to step down from one of the most challenging jobs in international justice when her mandate ends in June, with a mixed record of success at the Hague-based court.
Whoever becomes the court's third prosecutor since its formation in 2002 will be taking on a bulging file of difficult cases at a tribunal whose legitimacy is constantly under attack.
- 'Unacceptable' sanctions -
The new prosecutor's first tasks will include deciding the next steps on the probe into war crimes in Afghanistan and the hugely contentious investigation into the 2014 Israel-Palestinian conflict in Gaza.
The administration of then US president Donald Trump hit Bensouda and another senior ICC official last year with sanctions including a travel ban and asset freeze after she launched the probe that includes alleged US war crimes in Afghanistan.
Israel and the United States -- neither of which are ICC members -- have also strongly opposed the probe into alleged war crimes by both Israeli forces and Palestinian armed groups.
ICC judges however ruled last week that the court had jurisdiction over the situation in the Palestinian territories, paving the way for a full investigation after a five-year preliminary probe opened by Bensouda.
The new US administration under President Joe Biden has signalled a less confrontational line but has not said whether it will drop sanctions against Bensouda, who has attacked the "unacceptable" measures.
Among the four candidates to replace her, British lawyer and human rights specialist Khan has been a defence lawyer in several ICC cases, including for late Libyan leader Moamer Kadhafi's son Seif al-Islam.
Khan recently headed a UN special probe into Islamic State group crimes and called for trials like those of Nuremberg of Nazi leaders.
Ireland's Gaynor has previously represented victims of crimes at the ICC in probes including the Afghan war investigation and a case against Kenyan President Uhuru Kenyatta.
Spain's Castresana, a judge by training, previously headed a UN panel combating crime and corruption in Guatemala, but resigned in 2010 alleging "systemic attacks" by power-hungry officials.
Sicilian prosecutor Lo Voi meanwhile has led cases against Italy's Mafia and a major people-smuggling network.
- Mixed record -
Bensouda has had a mixed record even as she expanded -- some analysts say overextended -- the court's reach.
Under her leadership former Ivory Coast president Laurent Gbagbo was cleared of crimes against humanity, while former DR Congo vice-president Jean-Pierre Bemba was acquitted on appeal.
Kenya's Kenyatta also saw charges of crimes against humanity over electoral bloodshed dropped by Bensouda.
But Bensouda has recently secured high-profile convictions against Ugandan child soldier-turned-Lord's Resistance Army commander Dominic Ongwen and Congolese warlord Bosco "Terminator" Ntaganda.
She has also been credited with improving the prosecutor's office compared with her predecessor Luis Moreno-Ocampo, whose leadership was described as "autocratic" in a probe ordered by the ICC into the Kenyatta case.
The ICC is the world's only permanent war crimes court, after years when the only route to justice for atrocities in countries like Rwanda and the former Yugoslavia was separate tribunals.
Hamstrung from the start by the refusal of the United States, Russia and China to join, the court has since faced criticism for having mainly taken on cases from poorer African nations.