Toronto, who were promoted last month, are close to confirming the signing of the cross-code star on a lucrative two-year contract.
The Daily Telegraph revealed that Brian McDermott, Toronto's head coach, watched the 34-year-old play for the All Blacks in their World Cup semi-final defeat by England in Yokohama, in which Tuilagi played.
They later held face-to-face talks with Williams being offered a deal that includes a minority stake in the Canadian club.