An on-stage reunion between chart-toppers Jason Donovan and Kylie Minogue after more than 20 years at an outdoor concert has been axed.

The Hit Factory show, celebrating the music of Pete Waterman, was cancelled with hours to go because of safety fears due to heavy rain and mud in London’s Hyde Park.

Ms Minogue said she was sorry to hear today’s gig – for tens of thousands of people – had been pulled, adding: “I feel for all the fans.”

Promoters spent hours trying to get the site into a fit state after the ground was churned up by downpours and visitors at last weekend’s Wireless concerts.

But it was declared “unfit” yesterday morning. “The potential risk to staff and music fans was too great for the event to go ahead,” organisers said yesterday.

The show has been yet another casualty of the UK weather. Last month rain caused chaos at the Isle Of Wight Festival when visitors struggled to gain access to the sodden site, causing traffic gridlock.

The Hit Factory show – featuring many of the acts producer Waterman had catapulted to fame – was due to reunite Ms Minogue and Mr Donovan, performing their chart-topping hit Especially For You.

Along with his production team of Mike Stock and Matt Aitken,Waterman and his PWL record label were responsible for launching dozens of careers, and their pop tracks were almost instantly recognisable.

Ms Minogue said: “I am so sorry to hear that the concert tomorrow had to be cancelled. I feel for all the fans who had bought tickets to this special event.”

But they say other planned shows starring Bruce Springsteen and Madonna will go ahead unaffected.