Natural Resources Wales (NRW) said it is working to ensure that all relevant sites operating as MRFs are involved in the new sampling reporting regime, after a fall in the latest compliance figures.
Data on the new sampling regime for MRF operators in England and Wales showed a slight fall in the number of facilities that had reported.
In Wales, nine MRFs notified NRW with seven submitting data, one fewer than the previous quarter.
Now the Welsh regulator has said that 10 facilities said they were eligible to comply with the regulation, and it will continue to monitor these sites to ensure they comply with additional requirements.
NRW said it was aware that sites could fall into or outside the regulatory requirements due to no longer treating commingled recyclates, bulking waste on-site only or receiving lower than the 1,000-tonne annual threshold of mixed waste.
A spokesman said: “We recognise the importance of the effective implementation of these new regulations, and are working to ensure that we take a consistent approach which supports a level playing field across Wales.
“We continue to monitor all relevant sites for any changes that could lead to their inclusion or removal from the requirements of the definition of an MRF as set out in the regulations, and where necessary ensure that those sites notify us.
“We have checked evidence provided and verified the status with those facilities that we were expecting to have notified.”