Speaking exclusively to Sunday with Laura Kuenssberg, he said if ministers go ahead with plans to allow AI firms to use artists' content without paying, they would be "committing theft, thievery on a high scale".
This week the government rejected proposals from the House of Lords to force AI companies to disclose what material they were using to develop their programmes.
A government spokesperson said that "no changes" to copyright laws would be "considered unless we are completely satisfied they work for creators".
