ISTANBUL — The Turkish authorities will investigate a report that Germany has been spying on its NATO ally since 2009, a senior official said Sunday, saying the claims need to be taken seriously.

German weekly Der Spiegel reported that the German secret service the BND has been spying on Turkey since 2009, as well as accidentally intercepting at least one telephone conversation of US Secretary of State John Kerry.

"I am off the opinion that this needs to be taken seriously," said Mehmet Ali Sahin, the deputy chairman of the ruling Justice and Development Party (AKP).

"Definitely, our government and foreign ministry will carry out the necessary research about the allegations in the magazine," he added in televised comments.

But Sahin also said Spiegel's story needs to be approached "cautiously", recalling the rocky relationship between the prominent news magazine and the AKP.

During his victorious presidential election campaign, Prime Minister Recep Tayyip Erdogan, who will become president on Aug. 28, launched repeated attacks against Spiegel.

The magazine hugely irritated the ruling party with a major cover story — written both in German and Turkish — ahead of the polls that was sharply critical of Erdogan's strongman rule.