The 22-year old has been sidelined since suffering the injury during a fleeting appearance off the bench against Newport Gwent Dragons on New Year's Eve.
And Head Physio Chris Towers has confirmed the duration of his lay-off following an extensive investigation over the last week.
"Ashley suffered a significant ligament injury to his ankle during the New Year's Eve fixture at Rodney Parade," said Towers.
"We've conducted investigations over the course of the last week to determine the full extent of the ligament damage and plan his rehabilitation effectively.
"Based on the advice received, we are currently treating this as a 6-8 week injury so would expect to see him back in action by the end of February."