The shows were due to take place at London's 02 arena this week, on June 23 and 24 respectively, reported Digital Spy.
However, to give Jay time to rehabilitate from his surgery, the gigs will now take place on December 3 and December 6 instead.
"It is with great regret that again I have to disappoint people due to the ongoing problem with my back. I have never felt so frustrated with a situation as I feel now, and I am desperate to get back to form. After two operations I am only marginally more active, and I know I could never give the 125% energy I need to give to you good people a super show," he said.
"I want to thank all of you for the messages of support you have sent me. I can't quite believe how kind you all are. A thousand thanks," Jay added.
"Thank you all so much once again for your unerring love and patience, your posts have really picked me up. From a very wounded Buffalo. Lots of love, J.
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