THE HAGUE (Reuters) - War crimes judges in The Hague ruled on Friday that Libya must surrender the son of slain dictator Muammar Gaddafi to the International Criminal Court, where he is wanted for alleged crimes committed during the revolution that toppled his father.

Libyan authorities had argued that since they were already investigating Saif al-Islam's alleged crimes against humanity with a view to prosecuting him, the court had no jurisdiction under the principle that the court only intervenes where local legal systems are not up to the job.

Judges said Libya had not shown that it was investigating the same case as the court. Libya can appeal the ruling. Few analysts expect Libya to surrender Saif al-Islam, who is held by authorities in the mountain city of Zintan, where the writ of Libya's central government runs weakly.

(Reporting by Thomas Escritt; editing by Andrew Roche)