Libya ICC lawyer Melinda Taylor and colleagues fly out

Four staff members from the International Criminal Court (ICC) have left Libya on the day they were released after four weeks' detention on suspicion of spying.

They arrived in the Netherlands late on Monday night, the ICC said.

Their release came as ICC president Sang-Hyun Song was visiting Libya.

The team had been accused of spying while visiting Saif al-Islam Gaddafi, son of deposed Libyan leader Muammar Gaddafi, in the town of Zintan.

Saif al-Islam has been indicted by the ICC for crimes against humanity but Libya has insisted he should be tried by a Libyan court.

The ICC team flew out on an Italian military aircraft following a two-hour drive from the town of Zintan, says the BBC's Rana Jawad, in Tripoli.

They are still scheduled to appear before a court in Tripoli on 23 July for a final ruling on their case, a senior member of the Libyan attorney-general's office told the BBC.

"We expect them to come back for the hearing but if they don't, a ruling will be made in absentia," the source said.

During a news conference in the mountain town of Zintan, west of Tripoli, Mr Song offered an apology to the Libyan authorities for the "difficulties" caused by the mission.

He also thanked the Libyan authorities for their agreement "to release the Court's staff members so that they can be reunited with their families".

Mr Song "expressed his relief that the ICC staff members were well treated during their detention".

The ICC employees had been accused of jeopardising Libya's national security, the BBC's Rana Jawad in Tripoli reports.

One of the four, Australian lawyer Melinda Taylor, was accused of passing Saif al-Islam coded documents, allegedly written by his former right-hand man, during the team's visit.

Ms Taylor and her Lebanese colleague Helene Assaf, a translator, were then formally detained.

Their two other colleagues, Russian Alexander Khodakov and Spaniard Esteban Peralta Losilla, remained with them out of solidarity.

Last week, the ICC promised in a statement to investigate any claims of wrongdoing by its staff upon their release and to impose "appropriate sanctions" if necessary.

Ms Taylor was appointed by the ICC to help prepare the defence of Saif al-Islam, who was captured by the Zintan militia last November as he tried to flee the country.

The Zintan militia have refused to hand Saif al-Islam over to Tripoli, while the Libyan government is rejecting ICC demands to try him in The Hague.

Some have expressed concern that Saif al-Islam may not face a fair trial in Libya.

He was previously considered to be heir apparent to his father, Col Muammar Gaddafi, who was overthrown last year following a popular uprising and Nato air campaign mandated by the UN to protect Libyan civilians.

Col Gaddafi himself was killed after being captured during an assault on his hometown of Sirte in October.