The two police officers were shot at point blank range by two youths who stopped them on the pretext of wanting information, Le Jeune Independant newspaper said on Monday.
The killing occurred on the outskirts of the town of Miliana, 120km west of the capital, Algiers. The smaller but more violent of Algeria's two Islamic groups, the Armed Islamic Group (GIA), is known to operate in the region.
A passer-by was injured by a stray bullet during the attack, the paper said. The two youths who killed the police took their weapons and fled.
Meanwhile, a fighter was killed in the al-Akhdaria region, 70km southeast of Algiers, during an operation by security forces to round up hardliners, wrote Le Quotidien d'Oran newspaper.
Since the start of the year, 51 people, more than half of them fighters, have been killed in violence in Algeria, according to a toll compiled from official sources and the press.
However, violence blamed on hardliners has been down this year, a trend that started at the end of 2003, when the armed groups lost key members as a result of army raids on their strongholds.
The GIA and the Salafist Group for Preaching and Combat (GSPC) are the only forces still waging war against the secular government.
The civil war began in 1992 when the army intervened to call off the second round of elections an Islamist party was set to win.
In 2003, almost 900 people, including 430 fighters, lost their lives, while nearly 150,000 have died since the violence broke out in 1992.