The singer shared a "special bond" with her older sibling – who died on June 25 of acute Propofol intoxication – and has decided to dress in dark clothes as a mark of respect.

A source explained to Britain's The Sun newspaper: "Janet, like the rest of the Jackson family, has been left bereft by Michael's passing.

"As a mark of respect she has decided to only wear black clothes to express her grief, and she has had to go on a number of shopping trips to find suitable items to wear.

"She has resolved to mourn Michael's death for 12 months, and in June next year - on the anniversary of Michael's passing - her time of reflection will come to an end."

Meanwhile, Jermaine Jackson has blasted claims he is trying to "cash in" on his brother's death by planning a series of tribute concerts.

Jermaine told ET Online: "That is absurd. That is the most ridiculous thing ever. It is not about cashing in on what has happened. It is responsibility on all of our parts as brothers and sisters to keep his legacy alive.

"I would love to see something done in my brother's honour every year, because he was that well respected around the globe. So for the media to say this is absurd. It is stupid. It is crazy.

"Because we want the world to know we have created this as the Jackson 5 - that was the foundation of Michael's success, of Janet's success, of everybody's. How are we cashing in on something that we created?"