Queen of pop Madonna said to fans on the first night of her world tour that she feared she "wouldn't make it" after her near-death health scare.

She made the remarks on stage at London's O2 Arena, where she kicked off her much-anticipated "Celebration" shows after they were postponed when the singer was rushed to hospital in June suffering a "serious bacterial infection."

"I didn't think I would make it, and neither did my doctors. That's why I woke up with all of my children sitting around me," Madonna told her fans at the sold-out concert while holding her guitar, reports aceshowbiz.com.

She added: "I forgot five days of my life, or my death, I don't really know where I was. But the angels were protecting me. And my children were there.”

“And my children always save me, every time. If you want to know how I pulled through and how I survived, I thought, I have got to be there for my children. I have to survive for them."

Madonna then played an acoustic version of the Gloria Gaynor track 'I Will Survive', reports aceshowbiz.com.

After recovering from her illness at home in New York, Madonna told fans she was rescheduling her world tour in October.

There had been reports the singer had been exhausting herself in rehearsals for the shows, but before they were relaunched, it was reported she was in top health.

Her tour features a 45-song set list celebrating Madonna's 40-year career, with her opening night showcasing a series of raunchy outfit changes and a moment where she pulls her skirt over one of her dancer's heads while straddling his shoulders.