Sony Music is believed to be responsible for increasing the price of a Whitney Houston's album on Apple's iTunes store just hours after the singer died.

Initially, Apple came under fire for the pricing blunder, which saw Houston's The Ultimate Collection increase from £4.99 to £7.99 in the early hours of Sunday morning, but it is now understood that Sony Music upped the price.

Increasingly the wholesale price automatically caused the price on iTunes to rise; fans trying to buy the album at the old price were unable to do so and were all charged £7.99; as of Monday afternoon the price has been returned to £4.99.

Entertainment site DigitalSpy reported that some angry customers were accusing Apple of cashing in on the singer's death. One customer said: "The album itself is great so please don't be put off purchasing it, just that you will merely be lining some fatcat's pocket before Whitney's lifeless body is cold."

Another angry fan said: "To say I am angry is an understatement and I feel it is just a case of iTunes cashing in on the singer's death, which in my opinion is totally parasitic."

It is now believed that Sony Music, and not Apple, was responsible for the price hike; The Guardian said: "One insider close to the situation said the price hike was not a 'cynical' move - but that the wholesale price of Houston's The Ultimate Collection was wrong. The change in wholesale price boosted the album's retail price on iTunes."

Originally released in 1997, the album was the second top-selling album on the iTunes store by Monday morning, following the singer's death, which was announced on Saturday night after she was found dead in her room at the Beverly Hilton Hotel.

The singer, 48, died on the eve of the Grammy Awards ceremony, one day after being photographed leaving a late-night party looking exhausted.

The cause of death is being investigated. Police said there were no obvious signs of foul play.