At about 4:30pm Wednesday afternoon 34 sympathizers of the Kurdistan Workers' Party (PKK) – a group fighting the Turkish state and classified as a terrorist organization by the German government – evaded security and snuck into the studio.
They then asked the station to air their demand that PKK founder Abdullah Öcalan be released from the Turkish prison where he has been sentenced to spend the rest of his life.
When RTL refused, the protesters said they would not leave peacefully and the police were called.
That prompted a stand-off that lasted until night, as police tried to convince the protesters to go home.
When they refused, officers finally entered the building and forced them to leave. Although RTL said it wanted the protesters to face criminal trespass charges, the police emphasized that they had merely removed them and recorded their personal information.
It was not clear if legal charges would be filed.
The PKK protest drew predictable and immediate condemnation from both the German and the Turkish governments.
German Foreign Minister Guido Westerwelle called the incident unacceptable. "Germany and the European Union classify the PKK as a terrorist organization,” he underlined.
An RTL spokesman said Thursday that the network had been shaken by the situation and was trying to prevent it from happening again.
“We will definitely review admission controls,” said spokesman Christian Körner.
The PKK has been in a protracted armed conflict with Turkey since 1984 over the rights of the country's Kurdish minority. Many of its sympathizers live in Germany where they try to raise funds and awareness for their cause.
Although its members view themselves as fighting a liberation struggle, Turkey and many Western governments accuse the PKK of launching terrorist attacks and trafficking drugs.
The imprisonment of Öcalan is a particular bone of contention for the organization's sympathizers, who see him as a hero.