But Manoa, who left Northampton for Toulon last summer, still has three years remaining on a lucrative contract, meaning Saints could face a sizeable financial stumbling block.
The American is believed to be on a basic salary of more than £600k per year at the French giants and Saints would also have to reach an agreement with Toulon for his services.
But it is believed that Manoa could be open to a return to the club where he made his name.
The 31-year-old was Saints’ supporters’ player of the year in 2013 and 2014 and was a hugely popular figure after joining from San Francisco Golden Gate in 2011.
He scored 16 tries in 84 appearances for Saints, helping the club to claim an Aviva Premiership and Amlin Challenge Cup double in the 2013/14 season.
His first season at Toulon has been hampered by injury, but he has been back in action in recent weeks, helping to secure a second-placed finish in the Top 14.
Toulon will now face a semi-final as they seek to reach the French league’s showpiece, which will be held at Barcelona’s Nou Camp on June 24.