The Algerian coastguard shot dead two tourists who apparently strayed into Algerian waters on jet skis last Tuesday, with a third person arrested.
Fatima Tamni, from the Federal Democratic Left party, said the government must provide the public with an official statement on the incident.
“The tragic death of a Moroccan citizen, who is the holder of French citizenship as well, by live bullets from Algerian authorities, has sparked a lot of resentment and condemnation, and revealed a clear violation of international conventions,” she said in a written address to Morocco's Prime Minister Aziz Akhannouch.
“In view of this situation, and at a time when Moroccans have been awaiting clarification from the government, it only devoted a period not exceeding five seconds to comment on the tragedy … throwing the ball to the judiciary,” she added.
Ms Tamni demanded answers to appease the bereaved families and provide more information on the member of the group who was arrested.
There has been no official comment from either Algiers or Rabat about Tuesday’s incident at a time of increased tensions between the two North African countries.
Coverage of the incident on local news outlets was limited in both Algeria and Morocco.
An investigation was launched by the public prosecutor’s office in Oujda, the capital of north-eastern Morocco and a city bordering Algeria, on Wednesday, a judicial source told the official state news agency MAP.
Ms Tamni said the Algerian authorities had no need to use such excessive force.
“As per the Montego Bay Convention relating to maritime borders, there are several methods – other than killing – by which states’ territorial integrity could be protected,” she said.
Both Algeria and Morocco ratified the UN Convention on the Law of the Sea, otherwise known as the Montego Bay Convention, in 1996 and 2007 respectively.
Ms Tamni accused Algiers of violating the stipulations of the aforementioned UN convention.
Several Moroccan human rights activists have also condemned the incident and the lack of official response.
A protest is to take place in front of the Moroccan parliament next Monday.
The French Foreign Ministry released a short statement, describing it as “an incident involving several of our nationals”.
Paris said its “crisis support centre and our embassies in Morocco and Algeria are in close contact with our fellow citizens' families, to whom we are offering every support”.
Tuesday's deadly shooting comes at a time of increased tensions between Morocco and Algeria, exacerbated by a dispute over territory in Western Sahara.
Morocco has claimed control of the region, while Algeria has been backing and providing support for the Polisario Front, the main political actor attempting to receive international recognition for the Western Sahara’s autonomy.
As a result, the border between the two countries has been closed since 1994 and Algeria broke off diplomatic ties in August 2021, accusing Morocco of “hostile acts” – a decision Rabat called “completely unjustified”.
In July, Morocco's King Mohammed VI said he hoped for a return to normality and reopening of borders with Algeria.
However, Israel's recognition of “Morocco's sovereignty” over Western Sahara added to tensions with Algeria, which called the Israeli move a “flagrant violation of international law”.