“The principle of neutrality in public service prohibits such displays,” the interior ministry said in a telegram, a copy of which was seen by AFP on Friday.

Any decisions by mayors to fly the Palestinian flag should be referred to courts, the interior ministry said.

Israel’s war on Gaza is a hot-button issue in France, and several French mayors have already announced their intention to display the Palestinian flag on their town halls next week.

On Monday, France is set to formally recognise a Palestinian state at the UN General Assembly.

The warning from the interior ministry came after Socialist leader Olivier Faure called for the Palestinian flag to be flown on town halls on Monday, when Jewish worshippers also celebrate the Rosh Hashanah holiday, the Jewish New Year.

However, the telegram said any such display would amount to “taking sides in an international conflict”.

“It is therefore appropriate,” the telegram said, “to ask mayors who display such flags on their public buildings to cease doing so and, in the event of refusal or non-compliance” to refer those mayors’ decisions to administrative courts.

Israel has been under mounting pressure to wrap up its campaign in Gaza, where the war has created a humanitarian crisis and devastated much of the territory, and to bring home Israeli hostages held there.

Israeli Prime Minister Benjamin Netanyahu has accused Macron of pursuing a policy of “appeasement” of the Hamas rebels. Macron said Thursday that recognising a Palestinian state would isolate Hamas.

Several other leaders have announced their intent to formally recognise the Palestinian state during the UN summit.