An abnormal sound detected in the South Atlantic ocean around the time that an Argentine navy submarine sent its last signal last week was "consistent with an explosion," a navy spokesman said on Thursday.

Spokesman Enrique Balbi described the blast in the morning of November 15 as "abnormal, singular, short, violent" and "non-nuclear."

A huge sea and air hunt is being conducted for the ARA San Juan, which went missing with 44 crew on board.

However, experts said that had the submarine been submerged and unable to surface, it would probably have run out of oxygen today. The submarine had reported an electrical fault and was returning to base. 

The sound of the possible explosion was detected by the the Vienna-based Comprehensive Nuclear Test-Ban Treaty Organization, an international nuclear test-ban body that runs a global network of listening posts designed to check for secret atomic blasts.