German investigators said Monday they were probing an attack on a Jewish student outside a synagogue in Hamburg as attempted murder with anti-Semitic intent, a case condemned by Chancellor Angela Merkel as a "disgrace".

The 26-year-old student was badly injured on Sunday by a man who repeatedly struck him on the head with a shovel outside the synagogue where the Jewish community was celebrating Sukkot, also known as the Feast of the Tabernacles.

The assault came a year after two people were shot dead by an extremist who tried and failed to storm a synagogue in the eastern German city of Halle.

Jewish leaders and top politicians led condemnation of the latest attack, which Merkel's spokesman described as a "repulsive" assault.

"Such an attack is repulsive, no matter what investigations about the motivation and the condition of the perpetrator might show," said spokesman Steffen Seibert.

"And it must be clearly stated by everyone in this society: in Germany, every such act is a disgrace."

The suspect, 29, was arrested by police officers who were assigned to protect the synagogue in the northern city.

Dressed in combat fatigues, he had a piece of paper with a hand-drawn swastika in his pocket, said police and prosecutors in a statement.

"The current assessment of the situation suggests that this is an anti-Semitic motivated attack," they said, adding that investigators are treating the case as "attempted murder with grievous bodily harm".

'Intolerance' 

Ronald Lauder, leader of the World Jewish Congress, demanded action, saying that the attacker "must be held responsible as must all who engage in any expressions of hate or intolerance". 

Josef Schuster, president of the Central Council of Jews in Germany, said: "No one in the country should be blase about a situation where Jews here are repeatedly the target of hate."

He added that the case shows that security measures may have to be improved.

Last year's attack on the synagogue in Halle came on October 9 during Yom Kippur, the holiest day in the Jewish calendar. A neo-Nazi suspect is currently on trial for the crime.

Stephan Balliet, 28, who stands accused over the Halle attack had told the court his assault on the synagogue was "not a mistake".

Only last month Merkel spoke of her shame over rising anti-Semitism in Germany, even as the Jewish community warned that coronavirus conspiracy theories were being used to stir anti-Jewish hatred.

Anti-Semitic crimes have increased steadily in Germany in recent years with 2,032 offences recorded in 2019, up 13 percent on the previous year.

The uptick in hate against the Jewish community has sparked a round of soul-searching in Germany, which has in the last decades placed a huge emphasis on atoning for the murder of six million European Jews by Adolf Hitler's Nazi regime during World War II.

But the arrival in parliament of the far-right AfD, whose leaders openly question Germany's culture of atonement over WWII atrocities, has contributed to the change in atmosphere.

The arrival of more than a million asylum seekers, many from Muslim countries such as Syria, Afghanistan or Iraq in recent years has also played a role in growing hostility against Jews.

In an assault that sparked revulsion in Germany, a Syrian migrant was charged for lashing out with his belt in April 2018 at an Israeli man wearing a Jewish kippa skullcap.

Germany is now home to the third-largest Jewish population in western Europe, largely due to an influx of around 200,000 Jews following the collapse of the Soviet Union.