Berlin -Berlin has asked Cairo to explain why prominent Egyptian journalist Ismail Alexandrani was arrested on his return from Germany last month, AFP learnt on Thursday.
In a reply to queries from lawmaker Franziska Brantner over the arrest, deputy foreign minister Maria Boehmer wrote: "The government is following this case closely and has sought clarification from the Egyptian embassy".
It remained unclear whether Alexandrani had been detained over information provided by the Egyptian embassy during his trip here, Boehmer added in the letter seen by AFP.
The journalist's lawyers had said that he was detained on November 29 on charges of publishing false information and belonging to the banned Muslim Brotherhood.
A security official confirmed Alexandrani's arrest but refused to comment on any charges.
Thousands of activists, as well as several journalists, have been detained since then army chief and now President Abdel Fattah al-Sisi overthrew his Islamist predecessor, Mohammed Morsi, in 2013.
Brantner urged the German government to keep a close eye on the case, saying that the Egyptian embassy in Berlin should not be allowed to "throw such journalists to the wolves".
An expert on jihadist movements in North Sinai, where security forces are fighting an insurgency led by ISIS, Alexandrani was in Germany to deliver lectures on the political situation in Egypt, according to his wife Khadija Gaafar.
Known for his anti-regime writings and for criticising the military's role in politics, he is the second journalist to be detained in recent weeks after the military held prominent rights defender and reporter Hossam Bahgat for a day last month.
Human rights groups accuse Sisi of installing a repressive regime that has arrested thousands of activists, mostly Islamists, but also leftists and journalists.