Saudi Arabia, in a rare comment on its security operations, has confirmed it is working with German investigators to track Islamist militants behind bomb and axe attacks in Germany in July.

A Saudi interior ministry spokesman, General Mansour Al-Turki, said Saudi and German security experts had met and exchanged information over evidence showing that one of the attackers in Germany had been in contact through social media with a member of Islamic State using a Saudi phone number.

Al-Turki said the suspect was in an unspecified "country of conflict," but declined to say whether he was a Saudi citizen.

"The investigation is still ongoing between experts in both countries to try to find the parties to the case," Al-Turki told Reuters in response to a question on a report by news magazine Der Spiegel.

Saudi Arabia, though it says it is always ready to work with foreign countries to fight terrorism, rarely speaks publicly on specific cases.

Islamic State has claimed responsibility for an attack in Bavaria in which a 17-year-old refugee wounded five people with an axe before police shot him dead, and for a bombing in Ansbach, southern Germany, which wounded 15 people.

The 27-year-old Syrian, who carried out the Ansbach attack, had pledged allegiance to Islamic State on a video found on his phone, investigators said.

Spiegel said traces of the chat indicate that both men had been influenced by, and taken instructions from, unidentified people before the attacks.

German foreign ministry spokeswoman Sawsan Chebli told a news conference on Monday that Saudi Arabia had offered to help Germany investigate attacks in Germany claimed by Islamic State.

"Germany and other western countries have been successfully working together with Saudi Arabia on fighting terrorism for a long time," she said. Information passed on by Saudi Arabia had been key in helping prevent terrorist attacks in Germany in the past, she said.

German interior ministry spokesman Tobias Plate said the government welcomed Saudi Arabia's offer and added that cooperation with the security authorities there was of "significant value" but he declined to comment on the status of investigations. - Reuters