New Zealand Rugby tonight confirmed yesterday's report by the New Zealand Herald, releasing a statement saying it had accommodated Williams' request to have advertising from the BNZ and Investec removed from his Super Rugby playing jersey.
The dispensation was granted on the basis of Williams' conscientious objection to this category of sponsorship, taking advantage of a clause in his contract that makes allowances on the basis of genuine family, ethical or religious grounds.
Previously Williams had not been required to undertake promotional activities relating to categories of sponsors he had lodged objections to on religious grounds.
The midfielder then made headlines in his season debut on Saturday night, taping over the BNZ logos on his Blues jersey.
In the NZR statement Williams, a practising Muslim, clarified his preference was to avoid wearing logos from banks, alcohol brands and gambling sponsors on his team uniform.
"I want to be clear that this is nothing personal against the BNZ or Investec," he said. "My objection to wearing clothing that markets banks, alcohol and gambling companies is central to my religious beliefs and it is important to me to have been granted this exemption.
"As I learn more and develop a deeper understanding of my faith, I am no longer comfortable doing things I used to do. So while a logo on a jersey might seem like a small thing to some people, it is important to me that I do the right thing with regards to my faith and hope that people respect that.
"I know I'm not perfect. Every day I work hard to become a better person. I want to thank the Blues and New Zealand Rugby for working with me through this matter over the last couple of days and respecting my religion and accommodating my request."
NZR general manager of rugby Neil Sorensen said Williams' stand would be respected and thanked the affected sponsors for their understanding.
"Sonny holds clear religious beliefs in relation to this matter and we respect those," Sorensen said. "Conscientious objections need to be genuine, and we believe this is."