Lady Gaga has promised to keep performing until she nears her 60s.

The 39-year-old singer made a pact with fans at London's The O2 to be back on the same stage in 20 years "no matter what".

Speaking at a recent show on her The Mayhem Ball concert tour, she told the crowd: "It's been nearly 20 years, and look, I promise I am going to make a lot more music. I will come back.

"Every city that I go to I make a pact, I always say this. If I come back 20 years from now will you come to the show? You promise? I will be here no matter what."

Gaga was also full of praise for her supporters, admitting she still feels "happy" and "grateful" when fans buy tickets to see her shows, nearly 20 years since she shot to fame in the late 2000s.

She told the audience: "It's nice to see you. I'm so happy to be here. Thank you so, so much for buying a ticket to see our show tonight.

"We have been travelling the world with this show and it's not lost on you how happy I am and how grateful I am feeling.

"But it's been almost 20 years that we have been together. Can you believe it?"

While Gaga thanked her London-based audience late last month, she had to say sorry to supporters in Miami, Florida earlier in the month after cancelling a show when some were already inside the Kaseya Center venue.

On her Instagram Stories, she wrote: "Hi everyone I am really so so sorry but I need to postpone tonight's show in Miami.

"During rehearsal last night and my vocal warmup tonight my voice was extremely strained and both my [doctor] and vocal coach have advised me not to go on because of the risk it poses.

"I want to be hardcore and just push through this for you but I don't want to risk long term or permanent damage on my vocal cords.

"There is a significant risk based on all our combined experience with a show like ours and as you know I sing live every night - and even though this was a hard and agonizing decision I would be more afraid of the long term implications on my voice.

"I hope you can forgive me and accept my sincerest apologies for any disappointment, let down, inconvenience. I am so so sorry. I tried so hard to avoid this.

"I take serious care of myself to be able to put on this highly demanding show. I love my fans so much, respect you and hope you can accept my sincere regretful apology."