EX-MELBOURNE Rebels backrower Amanaki Mafi has been called into Japan's extended Rugby World Cup training squad despite facing an assault charge from his time at the Super Rugby club.

The Japan Rugby Football Union announced Mafi's inclusion following delays in legal proceedings in New Zealand, where the alleged incident involving former Rebels teammate Lopeti Timani occurred last July.

Mafi filed a not guilty plea in September after being charged with injuring with intent to injure, and both players were also fined $15,000 by the Rebels for their involvement in the late night bust-up.

Named Australian Super Rugby Player of the Year in 2017, Mafi left Melbourne to join Japan Top League club NTT Communications Shining Arcs.

Following the July incident, however, he was banned from all team activities until November.

The club then allowed him to play after "assessing his self-reflection and willingness to change his conduct", and  the 29-year-old released a letter of apology through the team.

With 22 Test caps, Mafi is considered one of the top players in the national side and starred in their 2015 World Cup campaign, which included an upset win over South Africa.

He will take part in Japan's next training camp.