A Lebanese journalist and her television channel have gone on trial before a UN-backed court in a case critics say raises questions about press freedom but which prosecutors say is essential to protect vulnerable witnesses.

Journalist Karma Khayat and the Lebanon-based Al-Jadeed TV station are accused of contempt of court for publishing purported witness lists from the investigation into the 2005 assassination of former Lebanese Prime Minister Rafik Hariri.

Mr Hariri and 21 others were killed in a waterfront bomb blast that upset a fragile peace in the eastern Mediterranean country, dragging it back to the brink of civil war.

The Special Tribunal for Lebanon was set up with UN backing to probe the killing after Lebanese politicians said their judicial system was not up to the task.

The tribunal has indicted five suspects, all of them linked to the Lebanese Shi'ite group Hezbollah.

They remain at large, meaning Ms Khayat will be the first person to appear in the dock in the courtroom since former Liberian President Charles Taylor went on trial for war crimes at another court that shared its premises.

Ms Khayat, who was then an editor at the pan-Arab Al-Jadeed station and is now its vice-chairman, says she published redacted lists that made it impossible to identify individuals to highlight the Special Tribunal's problem with leaks. The full list was published later by parties unknown, she said.

By targeting a high-profile TV station with a reputation for aggressive reporting, the tribunal was trying to intimidate other Lebanese media into silence, she said.

She could face up to seven years in prison and, along with and Al-Jadeed, a fine of up to £100,000 if convicted.