LOS ANGELES (Reuters) - Lady Gaga on Monday called off the European leg of her world tour, saying she was suffering from severe physical pain.

The singer, 31, who says she suffers from fibromyalgia, also cancelled an appearance at a music festival in Rio de Janeiro last week and posted pictures of herself in a hospital with a drip on her arm.

She said on her social media accounts on Monday she was disappointed at comments from people online that "suggest that I'm being dramatic, making this up, or playing the victim to get out of touring".

"It is complicated and difficult to explain, and we are trying to figure it out.

"As I get stronger and when I feel ready, I will tell my story in more depth, and plan to take this on strongly so I can not only raise awareness, but expand research for others who suffer as I do, so I can help make a difference," the singer added.

Her European tour to promote her latest album Joanne was due to start on Sept 21 in Barcelona.

"She plans to spend the next seven weeks pro-actively working with her doctors to heal from this and past traumas that still affect her daily life, and result in severe physical pain in her body," promoter Live Nation said.

The singer was hospitalised in 2013 for a hip injury and a new documentary, Lady Gaga: Five Foot Two, documents her struggles with chronic pain.