The family of two tourists, one of French-Moroccan nationality, shot dead last week by the Algerian coastguard are to launch a legal action in France, their lawyers announced on Sunday.

The two tourists were killed after straying on their jet skis from Moroccan waters into Algerian territory.

Lawyer Hakim Chergui, who is acting for the families of the victims, said the legal action would be submitted on Monday or Tuesday.

They are accusing the Algerian authorities of aggravated murder, attempted aggravated murder, the hijacking of a vessel and failure to assist a person in danger.

The break in diplomatic relations between Morocco and Algeria "does not justify the committing of the least crime and even less so the impunity of those responsible," said a statement from the lawyers.

"That is why, in the face of the silence of the Algerian authorities, on whose territory the killings took place, they have no other choice but to turn to the French courts..." the statement added.

The statement was issued shortly before the Algerian authorities released their own communique saying the jet skiers were shot after refusing to comply with orders to stop.

The brother of one of the men killed, who was with the group when the shootings happened, had told news websites the group accidentally strayed into Algerian waters after setting out from a Morocco beach.

The public prosecutor's office in the Moroccan city of Oujda, near the border with Algeria, has already opened an investigation into the incident, a judicial source told Morocco's official news agency MAP on Friday.