This isn't correct. Most white LEDs use a blue LED which is shone on some phosphors which then emit a broader spectrum of yellow light.

The ratio of yellow to blue light determines the colour temperature perceived. Some of that blue light will always get through, so white LEDs (even "warm" ones) will always have a blue light component to them.

http://www.photonstartechnology.com/learn/how_leds_produce_w...