“What is being proposed puts at risk the future of professional rugby across Swansea, Neath Port Talbot and Bridgend and the redevelopment of an historic rugby venue at St Helen’s,” the statement added.
“It is also important to recognise how little support these proposals appear to have across the wider Welsh rugby community.
“In particular, Ospreys and Cardiff supporters are united in their opposition and their concern about the future for their respective teams.”
The former Ospreys say “the time is right to speak up” over the WRU and Y11 plans.
They say they are willing to meet the union, either individually or collectively, to share their “experience” and “help shape a positive future for Welsh rugby”.
“What the game needs is confidence, consistency and collaboration – not constant shifts in direction, where four teams, then two, then three are all presented as the ‘optimal’ solution within a single year,” the statement added.