Sony has cancelled plans to introduce two portable MP3 players under its Aiwa brand in April.

The company had planned to include radio tuners in these devices, but has cancelled their launch because of "problems with the built-in FM radio tuners."

The AZ-FS256 and AZ-FS1 players were announced last month, but the tuners did not function properly with the other digital music functions, Sony said.

"It is extremely regrettable that this product could not go on sale, and we are very sorry this happened about a product we had announced," Sony spokesman Daichi Yamafuji said.

Sony is currently attempting to merge with BMG in a move for music industry hegemony that Apple opposes, as the Japanese giant would then be able to exercise what the Californian computer maker sees as undue influence over the evolving digital-music market. Sony has announced plans to introduce its own digital music download services.