German police have detained more than a dozen men in three cities suspected of damaging a synagogue with stones, burning Israeli flags and starting a fire at a memorial for a Jewish house of prayer destroyed during the Nazi pogroms of 1938.
German politicians on Wednesday condemned the three separate incidents as anti-Semitic attacks, which coincided with escalating cross-border violence between the Israeli military and Palestinian militants in the Gaza Strip.
Police said three men in their early 20s were detained on Tuesday night and released after admitting to throwing stones at the window of a synagogue in the city of Bonn and burning an Israeli flag.
The suspects told police the Gaza-Israel violence had motivated them to throw stones at a synagogue.
Civilians on both sides took cover as Israel carried out hundreds of air strikes in Gaza on Wednesday and Palestinian militants fired multiple rockets at Tel Aviv and the southern city of Be'er Sheva. At least 49 people in Gaza and six in Israel have been killed in the region's most intense hostilities since a 2014 war.
In the northwestern German city of Muenster, police said they had detained 13 men who gathered outside a synagogue and burned Israeli flags. They have been charged with holding an illegal public gathering.
Armin Laschet, premier of the state of North Rhine-Westphalia (NRW) where the incidents occurred, said police would boost security at Jewish sites in the region, which borders on Belgium and the Netherlands.
"We will tolerate no anti-Semitism," said Laschet, who is the chancellor candidate for Angela Merkel's conservative bloc in the next national election in September.
In Duesseldorf, the NRW capital, attackers set on fire a garbage bag over a stone commemorating the Grand Synagogue in the city that was destroyed during Kristallnacht, a spree of looting and destruction of Jewish property across Nazi-ruled Germany and Austria in November 1938.
"This anti-Semitic hate is a disgrace," German Justice Minister Christine Lambrecht said. "Synagogues and Jewish sites should be firmly protected."