(CNN) -- Turkey's top diplomat angrily rejected U.S. newspaper reports alleging the Turkish government leaked Israeli intelligence secrets to Iran.
"This is just a smear campaign. This is not true. It is dirty propaganda," Foreign Minister Ahmet Davutoglu said, according to a ministry spokesman.
Davutoglu was referring to a column published in the Washington Post on Thursday. Citing "knowledgeable sources," the Post's David Ignatius reported that in early 2012, the Turkish government revealed to Iranian intelligence "the identities of up to 10 Iranians who had been meeting inside Turkey with their Mossad case officers."
The Mossad is Israel's intelligence service.
The reported leak took place at a time when relations between Turkey and Israel were at an all-time low, after Israeli commandos killed eight Turks and an American activist during a botched 2010 raid against the Mavi Marmara, a Turkish aid ship seeking to break the Israeli blockade of Gaza.
Until then, Turkey and Israel had enjoyed decades of close military, intelligence and economic ties.
"With the full knowledge of the Turks, we used to use the Turkish soil in order to run intelligence operations," said Danny Yatom, a retired Israeli major general who spent several years running Mossad.
Speaking in a conference call with journalists, Yatom said Israel likely reduced its intelligence-sharing with Turkey after the rupture in relations following the Mavi Marmara raid.
But, he added, "this information that was transferred by the Turks to the Iranians about a year ago, this is information that they (the Turks) might acquire from Israel many years ago."
Washington, a close ally of both Turkey and Israel, has sought to smooth over differences between the Middle Eastern countries.
Earlier this year, U.S. President Barak Obama helped broker a telephone apology for the Mavi Marmara raid from Israeli Prime Minister Benjamin Netanyahu to his Turkish counterpart.
On Thursday, Turkish officials suggested that the Washington Post report was part of a broader effort to discredit Turkey's top spymaster, Hakan Fidan.
A week ago, the Wall Street Journal published a profile of Fidan, who is the head of the Milli Istihbarat Teskilati, or MIT, Turkey's main intelligence agency.
The article suggested Fidan was the architect of a policy that has funneled weapons and money to rebels in neighboring Syria.
Turkey has been one of the most vocal supporters of the Syrian opposition throughout civil war of the past two and a half years. The Syrian National Coalition, one of the main opposition groups in exile, opposition activists and rebels have been hosted in Turkey, which has also provided health care to injured fighters. In addition, CNN journalists have witnessed weapons being smuggled across the border from Turkey to Syrian opposition groups.
But in recent months, several hard-core al Qaeda-linked fighting groups have begun challenging more moderate rebel factions for control of northern Syria. Last month one such group, the Islamic State of Iraq and Syria, drove Syrian rebels out of the northern border town of Azaz.
Since then, ISIS militants have repeatedly clashed with rebel groups, which continue to control a key customs terminal on the border between Turkey and Syria. Turkey, meanwhile, has kept the border gate firmly closed.
This week, the Turkish military announced its artillery fired at ISIS positions near Azaz in retaliation for a suspected ISIS mortar shell that landed near the Turkish border town of Kilis.
One Turkish expert suggested the artillery strikes against al Qaeda-linked targets should be interpreted as a message to Turkey's NATO allies.
"What the Turks did yesterday, is to try to send a message to Turkey's critics, especially in the West, that the Turks have not gotten too cozy with the jihadists," said Henri Barkey, a professor of international relations at Lehigh University.
This was not the first time Turkish army has engaged in cross-border artillery duels along the frontier with Syria.
As the warring parties have grown increasingly fractured, reports say Turkish military units have fired at Syrian government forces, rebels groups, and even Kurdish militias.
"Our engagement rules compel the military to strike back whenever we see a threat to our own borders," said a Turkish government official, speaking to CNN on condition of anonymity.