ALBANY — Gov. Cuomo yesterday rejected a bill to mandate an extra 80 hours of training for city firefighters — siding with Mayor Bloomberg, who was opposed because of the costs.

The bill, passed by state lawmakers, would have required firefighters to get an extra 80 hours of training each year on city ordinances and fire- and building-construction codes.

Cuomo cited Bloomberg’s opposition to the measure, which the city estimated would have cost the FDNY an extra $20.5 million a year.