Germany's Angela Merkel Wednesday defended the cancellation on security grounds of a football match meant to honour the Paris attack victims, while her interior minister endured mockery for leaving the public in the dark about the reason.

The chancellor -- who had been due to attend Tuesday's German-Netherlands friendly in Hannover, widely billed as a "freedom match" after Friday's jihadist violence -- said: "I was as sad as millions of fans that the cancellation had to happen".

"These are difficult decisions, perhaps the most difficult decisions in balancing liberty and security," she said. "But yesterday it was decided, correctly, to err on the side of caution."

She thanked citizens, fans and the two national teams for their understanding when the match was scrapped after what police said was a bomb threat, and expressed gratitude to security services for working to keep the public safe.

Interior Minister Thomas de Maiziere said late Tuesday that the match was called off over an attack threat but declined to say what it was, citing the need to protect intelligence sources.

Another reason to keep quiet, he said, was that "part of the answer to the question would make the public feel unsafe" -- a statement that was widely ridiculed on social media for only heightening public fears.

On Twitter the hashtag #DoItLikeDeMaiziere quickly became a trending topic in Germany on Wednesday, with users adapting the minister's phrase to a host of everyday scenarios.

"Honey, is it my child?" a man asks his wife in one tweet, only to be told "part of the answer would only unsettle you". Other question-answer scenarios started with "Honey, how was I?" and "Was the World Cup in Germany paid for?"

Another popular tweet showed a picture of de Maiziere standing with Merkel and asking her: "How do you like me as interior minister?"