Members of the European Parliament have demanded an end to the use of sonar devices believed to cause the strandings and deaths of dolphins and whales.
Deep-diving whales are most affected
A 100,000-signature petition was delivered to Nato headquarters in Brussels on Monday calling for a ban on the devices, which are used to detect submarines.
Their move comes amid growing concern about the effects of soundwaves from underwater military sonar equipment.
Nato officials have agreed to meet the delegation to accept the petition signed by nearly 100,000 EU citizens.
MEPs argue the use of low frequency active sonar by Nato without proper studies into its environmental impact is in breach of the UN convention on the law of the sea.
"The latest research removes any doubt that military use of Low Frequency Active Sonar (LFAS) is responsible for the deaths of thousands of marine mammals, some of them endangered and protected species,"UK Green MEP Caroline Lucas, among the campaigners handing in the petition.
"Nato must immediately cease using the devices, in line with the clearly
stated wishes of thousands of European citizens who have signed this
The action comes days after British and Spanish scientists argued the sonar signals may cause marine mammals internal injuries at close range.
They carried out post mortem examinations on beached whales that became stranded along the Canary Islands last year.
Writing in the journal Nature, scientists described how 14 whales died during a naval exercise in the Canary Islands.
Their report suggested the sonar waves confuse the animals' sense of depth, causing them to surface quickly and suffer blood clots and fatal decompression sickness.
Environment groups have argued for years that sonar is a threat to cetaceans (whales, dolphins and porpoises).
But the scientists discovered damage to the livers and kidneys of animals they examined, including gas-filled cavities.
They said the bubbles they found in the animals' tissues resemble those found in divers affected by decompression sickness (DCS).
Images copyright and courtesy of Guayarmina Brito.