Prince performed secret charity work in every city he performed in, according to his ex-wife Manuela Testolini.

The late singer passed away at 57 last April (16), having already cemented himself as a music icon, but some fans may be unaware he worked just as hard on philanthropic efforts as he did on writing songs.

"He was definitely an aware guy," Manuela tells Rolling Stone. "From his earliest music, he was talking about social change and telling people not to be complacent. He really wanted to wake people up. He wanted to make sure they were active."

Prince established his own charity, Love 4 One Another, in the 1990s and the pop star worked with bosses at the organisation personally to ensure needy citizens in cities he visited on tour got help.

"He went with how the spirit moved him each day," explains Manuela, who worked for Love 4 One Another before she married Prince in 2001. "They were doing projects ranging from building community gardens to helping domestic shelters. I wasn't aware at the time, but when Prince would visit different cities for a concert, he would have work going on to complement the places he visited."

Manuela claims Prince was like a shadow operator when it came to charity, noting he wanted to keep his name out of the conversation so his fame would not overshadow the good work being achieved.

"He wanted to be a catalyst for other people," she recalls. "He would see a family on TV that was having trouble - they didn't have health insurance and had trouble meeting the needs of a sick child - and instead of saying, 'Wow, that's really sad,' he would leave a note on my desk saying, 'Call this TV station and find out where these people are so we can help them.' It was ongoing."