Fijian human rights advocate Shamima Ali called for the "immediate withdrawal" of Nasilasila from the Wardens team, saying it was "beyond belief" that he was allowed to represent the government department.
She said she was appalled at the inclusion of the convicted rapist in the side competing in the Super 7s series at Nadi's Prince Charles Park.
"We demand his immediate withdrawal from the team and totally condemn Nasilasila's inclusion," Ali said.
"He is a convicted rapist and it is beyond belief that the Fiji Corrections Service has allowed him to play in the Wardens side - he is not a warden, he is an inmate," she said.
Ali also demanded answers as to why Nasilasila was allowed to play when he was convicted in a court of law.
"This is sending out a terrible message to rapists and would-be rapists," she said.
"Rape is a heinous crime and once a person is convicted, they need to serve out their sentence - not be allowed to play rugby at their leisure.
"We demand an answer from the Commissioner of the Fiji Corrections Service and the courts as to how this was made possible.
"The government has a robust plan for eliminating violence against women and a National Action Plan under development - this kind of incident actually negates all the good work done by the State and by NGOs in this area."
Govt slams Nasilasila's participation: 'Continuous disregard of the law'
Fiji's Ministry for Women has also condemned Nasilasila's participation at the rugby tournament.
Minister Rosy Akbar said Nasilasila was not a warden but someone who was serving time in prison for rape.
"It is shocking that the Fiji Corrections Service team have even considered his participation," Akbar said in a statement posted on the Fijian government's official Facebook page.
"This is a continuous disregard of the law and in fact a mockery of the justice system in this country.
"Rape is a very serious crime and such privileges given to persons convicted of such a heinous crime are just not on. This has to stop. It sends the wrong message to the community."
Akbar said Nasilasila remained a convicted person and was still serving a sentence.
"The ministry calls for the Commissioner of Fiji Corrections Service to immediately intervene and remove Nasilasila from any further involvement in rugby until he has completely served out his sentence."
The Fiji Corrections Service has been approached for comment.
Bid for appeal against conviction
Last September, Nasilasila appealed against his conviction and filed a bail pending appeal application which was also refused by Acting Resident Judge, Justice Chandana Prematilaka.
Nasilasila had appealed on a number of grounds including that the judge erred in law by overturning the unanimous not guilty decisions of the assessors, the grounds to how his case was handled, and the caution interview with police in 2018.
Justice Prematilaka highlighted that Nasilasila's disapprovals and grounds were due to the ineptitude of his trial counsel and "therefore it is not necessary to consider the other two factors under section 17(3)".
"Section 17 states that the Court of Appeal shall not entertain any appeal made under the provisions of this part unless the appellant has fulfilled all the conditions of appeal as prescribed by the rules of court."