Many musicians turned their profile pictures turquoise on Sunday (29Mar15) and encouraged their followers to do the same and share the hashtag #TIDALforALL to promote the new music portal Jay Z is set to relaunch on Monday (30Mar15).

The hip-hop star began it himself by writing on Twitter.com, "The Tides They Are-A Changing' #TIDALforALL" and his pal West added, "Together, we can turn the tide and make music history. Start by turning your profile picture blue. #TIDALforALL."

Jay Z's wife Beyonce, Madonna, Nicki Minaj, LL Cool J, Arcade Fire and Coldplay also joined the movement by turning their profile pictures turquoise across all their social media platforms.

However, the co-ordinated effort has been hit by a backlash from fans for employing activism tactics to promote an app which helps musicians earn more money rather than using their voice to publicise a genuine charity campaign.

One Twitter user writes, "So proud of the upper echelons of the music industry all banding together to make Jay Z some money. #TIDALforALL" and another adds, "I hate it when #TIDALforALL is disguised as a charity when it's an overpriced product launch. Disgusting," while one other writes, "Multi-millionaires doing an awareness campaign for their favourite charity: their bank account #TIDALforALL".

Tidal, which Jay Z recently purchased from a Swedish company for $56 million (£35 million), is a subscription service that users can access for $19.99 (£12.50) a month. The rapper will officially relaunch it in New York on Monday.