BERLIN, December 21. /TASS/. Turkey has the ability to close its border with Syria to deprive terrorists of an opportunity to sell oil and purchase weapons but fails to do so, co-chair of the Left Party faction in Germany's Bundestag Sahra Wagenknecht told TASS on Monday.

"Those who really want to defeat IS (the Islamic State terrorist group outlawed in Russia) must exert pressure on the godfathers of terrorism in Turkey and in the Gulf States," the politician said. "However, the German government acts in a different way."

Instead, it authorises the supply of arms to Gulf countries and, amid the migrant crisis, "rolls out a red carpet before the Turkish government".

"That’s utterly irresponsible," she said, adding that "it was necessary to put pressure on Turkey so that it finally closes its border with Syria and blocks the way for oil, weapons and jihadists".

"That could really weaken IS but Turkey does nothing," she said.

According to Wagenknecht, in the Turkish government there are some supporters of the Islamic State group and by shooting down a Russian military plane over Syria Turkey threw off the mask of respectability.

"The Turkish government follows the my-enemy’s-enemy-is-my-friend rule. [Turkish President Recep Tayyip] Erdogan’s number one task is to oust Syrian President Bashar Assad and defeat the Kurds," she said. "The Assad regime and the Shiites’ influence in the region are a problem for Saudi Arabia and for other Persian Gulf states. So both provide covert support for the Islamic State to restrict that factor."

Wagenknecht believes that by attacking a Russian military plane the Islamic State’s sympathizers in the Turkish government have thrown off the mask of respectability.

"It is to be hoped that this deliberate act of sabotage will not have lasting effects on diplomatic efforts," she said.

A Turkish Air Force F-16 fighter jet shot down a Russian Sukhoi-24M fighter bomber on November 24. Ankara claims that the Russian plane had violated the country’s air space.

The Russian Defense Ministry replied that the Sukhoi-24 bomber had remained over Syria all the time and there was no intrusion.

Russian President Vladimir Putin has warned that the attack on the bomber will entail dire consequences for Russian-Turkish relations. He slammed the Turkish Air Force’s attack against the Russian plane that was participating in the anti-terrorist operation in Syria and posed no threat to Turkey as a "stab in Russia’s back.".