SAR Malta Network on Monday called for a public inquiry into the death of five people during a rescue operation in Maltese waters last week.
The migrants died on Friday when the boat they were in capsized some four miles off Malta during a rescue operation by the Armed Forces of Malta.
A total of 29 people survived: eight of whom were injured and hospitalised while the remaining 21 were taken to the Safi detention centre.
Human rights activists have since expressed concern over their detention. The government assured they were receiving psychological support
On Monday, SAR (search-and-rescue) Malta "demanded a comprehensive and public inquiry into this unnecessary loss of life", which it said added five more souls to the 2,500 people who drowned crossing the Central Mediterranean just last year.
The 34 people aboard the boat had a right to timely rescue, it said, adding that the survivors should be released from detention.
According to Maltese law and policy, vulnerable people should not be detained.
SAR Malta describes itself as a network of individuals and organisations concerned with the loss of life at sea.
"We act as an observatory and a monitor of SAR activities in the Maltese search and rescue zone. We contextualise this to broader migration and border control policies in Malta," a spokesperson told Times of Malta.
"We note that the Maltese authorities deployed a rescue mission in this case, as is their responsibility under international law throughout Malta’s search and rescue zone. We hope this signals a wider shift in the policy of non-assistance and the abandonment of people in distress that has characterised Maltese search and rescue in recent years," they said in a statement.
The network welcomed "the break from the secrecy" surrounding such rescue operations: "We trust this will become standard practice, and that more information will be shared on this particular case".
However, it said significant questions remained about the timing of the rescue operation, why the people in distress were not rescued earlier and whether standard search and rescue procedures were followed - including the availability of a RHIB and the means of communication with those on board.