The U.N.-backed Special Tribunal for Lebanon says Interpol has issued its highest-level international alerts for four suspects in the 2005 assassination of former Lebanese Prime Minister Rafik Hariri.

The court's Beirut spokesman, Martin Youssef, said Sunday that Interpol circulated the so-called “red notices” against each of the accused at the request of the Netherlands-based tribunal. Those notices are not international warrants, but are requests that the wanted person be arrested with a view to extradition.

Youssef said the alerts will not be published because the contents of the tribunal indictments remain confidential.

The U.N.-backed court handed indictments and arrest warrants in the case to Lebanon about a week ago. Lebanese officials say the documents accuse members of the Iranian-backed Hezbollah militant group of carrying out Mr. Hariri's assassination.

The Shi'ite militia group dominates the new Lebanese government formed last month by Prime Minister Najib Mikati. Hezbollah has thousands of guerrilla fighters, making it unlikely that authorities would be willing – or able – to detain the men.

Hezbollah denies any link to the 2005 assassination and its leader, Hassan Nasrallah, said earlier this month that authorities will never arrest the indicted members of his group – which accuses the tribunal of being a U.S. and Israeli tool.

Rafik Hariri's son, former prime minister Saad Hariri, has said the arrest warrants represent a “historic moment” for Lebanon. He urged Mr. Mikati's government to cooperate with the tribunal.

In January, Lebanon's president appointed Mr. Mikati as prime minister to replace Saad Hariri. Mr. Hariri's unity government collapsed that month after Hezbollah quit in protest of the tribunal's investigation.