Mae Gweinidog yr Economi Ken Skates wedi ysgrifennu at ddegau o filoedd o fusnesau yng Nghymru yn eu hannog i sicrhau eu bod yn cymryd y camau angenrheidiol i baratoi ar gyfer diwedd cyfnod pontio'r UE.
Economy Minister Ken Skates has written to tens of thousands of businesses in Wales urging them to make sure they are taking the necessary steps to prepare for the end of the EU transition period.