Morocco: Jet ski tourists killed off the coast
They were part of a group of four people with dual French-Moroccan nationality who had set off from the Moroccan resort of Saïdia.
A third member of the group was arrested by coastguards patrolling the closed border between the two countries.
The two nations have a long history of tension as they continue to dispute the Western Sahara.
The border between the two countries was closed in 1994, and Algiers severed ties two years ago. Algiers has accused Morocco of hostile acts, an allegation rejected by Rabat.
The shooting sparked anger in Morocco after a fisherman posted images of a lifeless body floating in the sea.
Mohamed Kissi was the only one of the group of four to return to Morocco, the AFP news agency reported, citing Moroccan media.
«We got lost but we kept going until we found ourselves in Algeria» said Mr Kissi, whose brother Bilal was killed. He added that the group had also run out of fuel.
«We knew we were in Algeria because a black Algerian rubber dinghy approached us» and those on board «shot at us» he said.
«Thank God I wasn’t hit, but they killed my brother and my friend», he added.
Mr Kissi denied that the group had tried to flee when they were discovered by the coastguard, telling local media that his brother had tried to talk to the authorities before being shot.
«They arrested my other friend. Five bullets hit my brother and my friend. My other friend was hit by a bullet».
Mr Kissi said that he then tried to swim back to Saïdia and was eventually picked up by the Moroccan navy.
His cousin, actor Abdelkarim Kissi, called on the Moroccan authorities to bring the case before the international courts.
«They killed Bilal Kissi, my little cousin», he wrote on social networks.
«His only crime was to have crossed Algerian territorial waters; he was on holiday with his friends.
Abdelali Merchouer has been named as the second man killed.
His body is still in Algeria, according to the Moroccan news website Le360.
The man arrested by the Algerian coastguard, Smail Snabe, reportedly appeared before a prosecutor on Wednesday, but no details were given.
A Moroccan government spokesman declined to comment on the shooting, telling AFP that it was a « matter for the judiciary ».
Algeria had no immediate comment.
The two countries share a border almost 2,000 km long, which has been a source of tension since their independence from French colonisation.
It was closed in 1994 for security reasons after Islamist militants bombed a hotel in the historic Moroccan city of Marrakech.
Justine Adjoa