Brussels | Europe faces a “huge risk of terrorist attacks" over the Christmas holiday period due to the fallout from the war between Israel and the Palestinian militant group Hamas, the European Union's home affairs commissioner warned on Tuesday.

The warning came as French investigators probe a fatal weekend attack near the Eiffel Tower in Paris. Questions were raised about the mental health of the suspect, who swore allegiance to the extremist Islamic State group before stabbing a German-Filipino tourist to death and injuring two other people with a hammer.

"With the war between Israel and Hamas, and the polarisation it causes in our society, with the upcoming holiday season, there is a huge risk of terrorist attacks in the European Union," EU Home Affairs Commissioner Ylva Johansson told reporters.

"We saw (it happening) recently in Paris, unfortunately we have seen it earlier as well," she said, as EU interior ministers gathered in Brussels. She provided no details about any information that might have led to her warning. Her office did not immediately respond to requests for details.

Johansson, whose brief includes security and immigration, said that European Commission will provide an additional 30 million euros ($32.5 million) to help bolster security in vulnerable areas, notably places of worship.

German Interior Minister Nancy Faeser sent her condolences to France over the attack, and said that it highlights “just how acute and how serious the threat posed by Islamist terrorism is currently in the EU.” “The war in Gaza and Hamas' terror are exacerbating this situation,” she told reporters.