Fears over late Tir Gofal payments have been raised by Preseli Pembrokeshire AM Paul Davies.
He has received a number of complaints from farmers having difficulties getting their payments.
"It seems that the reason is that the Welsh Assembly Government has had to change its rules in order to work within new European Union regulations," said Mr Davies.
"I understand that the Welsh Assembly Government may not have prepared for these regulations or did not receive sufficient warning in order to prepare for them."
There are now fears that there may be lengthy delays in receiving the grants.
Mr Davies has now pressed both the First Minister Rhodri Morgan and the Rural Affairs Minister Elin Jones for details about when the payments will be made.
