After a period of relative calm, more than 60 people, mainly civilians, have died in a string of attacks. The most lethal came on Saturday in the Bechar region in the southern foothills of the Atlas mountains, in which 29 people were murdered. At least two had their throats cut - the now familiar "signature" of Islamic rebels.
No one has claimed responsibility but the latest carnage is assumed to be the work of the Armed Islamic Group (GIA) or the Da'wa wal Djihad (Appeal and Struggle) organisation, both of which reject the cease-fire announced in June between the government and the more moderate Islamic Salvation Army (AIS).
That agreement was followed by the announcement from Abdelaziz Bouteflika, Algeria's first civilian President, of further measures including an amnesty for thousands of Islamic activists and rebels, subsequently approved by the parliament in Algiers.
But the referendum is crucial if Mr Bouteflika, elected in controversial circumstances in April, is to gain the genuine popular mandate he needs to strengthen his own hand in dealing with the cabal of generals who hold ultimate power in Algeria.
The President has made clear his overriding priority is to end the war, which has claimed more than 100,000 lives since 1992 when the authorities cancelled elections that the still outlawed Islamic Salvation Front (FIS) looked certain to win. But even now, a hardline faction of the military remains unhappy at any concessions to the insurgents.
The latest spate of killings risks playing into its hands, curtailing President Bouteflika's room for manoeuvre.