Turkey has presented an official protest to Austria after it emerged that a senior leader of the outlawed Kurdish Workers' Party (PKK) flew from Vienna to northern Iraqi province of Arbil, despite an Interpol red bulletin on him and an ongoing court trial on terror-related charges in France, local newspaper Zaman (Time) reported on Thursday.

Christian Steiner, the charge d'affaires of the Austrian embassy in Ankara, was summoned on Wednesday to the Foreign Ministry, where officials expressed "sadness" over what appeared to be a scandalous escape by PKK member Riza Altun from Vienna to Arbil in northern Iraq.

"Ankara has great difficulty in understanding the use of release by a court in Austria on July 13 of Altun, who is one of the top leaders of the PKK," a Turkish diplomat told Steiner.

The diplomat also noted that the release decision was made by an Austrian court despite the existence of a European arrest warrant issued for him by France as well as an Interpol red bulletin for his arrest issued back in 2002.

"They shouldn't have let a terrorist wanted by Interpol leave their territory in this manner. It is unacceptable that he took a flight and was transported from one country to another," said Foreign Minister Abdullah Gul earlier in the same day during an election campaign trip to the central Anatolian province of Kayseri.

Altun is believed to be in charge of financing for the PKK in Europe. He was detained in France as part of an investigation into the terrorist group in February but was later released pending trial. The French authorities had also banned him from traveling out of Paris.

However, early this month Altun appeared in Vienna, where he was detained, reportedly for carrying a false passport. Turning a blind eye to the ongoing court trial in France and the Interpol red bulletin, Austrian authorities allowed Altun to take a flight on July 13 from Vienna to Arbil.

The PKK, listed as a terrorist organization by Turkey, the United States and the European Union, has increased attacks on Turkish troops in southeastern Turkey in recent months that led to Turkey's mounting intention of an incursion into northern Iraq to crush the PKK.