Minimum visibility (that's Met Vis, not RVR) for a CIRCLING APPROACH found in PANS-OPS Part 1 - Section 4 Chapter 7, page 5 (and also Appendix 1 to JAR-OPS 1.430) for aircraft categories A to D: 2400m for Cat C.
Minimum RVR for a VISUAL APPROACH in Appendix 1 to JAR-OPS 1.430: An operator shall not use an RVR of less than 800m for a visual approach - no other guidance given. From memory the old UK CAP 360 document suggested something like the higher of 800m or the highest non-precision minimum RVR for a straight-in approach to the intended landing runway.