Sir David Attenborough fans were left bemused after noticing a change in the broadcaster's distinctive voice during his new show Asia on Sunday.

The 98-year-old narrates the series, which explores the wildlife and natural wonders of the planet’s largest continent, with the latest episode following those dedicating their life to saving animals.

However viewers couldn't help but point out that Sir David's voice appeared to be at a much higher pitch than usual and were convinced it was a result of autotune or AI. 

Taking to X one person said: 'Anyone else confused as to why the voice of the amazing David Attenborough sounds different? It’s like it’s been auto tuned? #Asia'.

While another replied: 'Yes! We are. It’s not quite right, is it? It’s definitely been tweaked in some way. To begin with I thought it was someone else narrating'. 

'Definitely been tweaked': 'David Attenborough now sounds like a bad David Attenborough impersonator - slightly off, like the new faux-Sallis Wallace. Perhaps he's AI now?': 'Hi @BBCEarth Not sure having David Attenborough sound like a chipmunk is a fine example of post-production. What a shame. #bbcearthasia'

Last week Sir David gave a sneak peek into his latest nature documentary after the crew crisscrossed the continent of Asia over four years. 

The series shows animals as far north as the Baikal seal in Russia and all the way down south to the Pangolin in Singapore.    

Thanks to their hard work, never-before-seen footage of rare animals was filmed.

This includes a Gobi bear, one of just 32 left in the world, and it marks the first time the endangered species has been captured on camera. 

The crew also managed to snap a footage of one of the rarest birds in the world - the Javan green magpie.

In Sri Lanka, the camera crew tried 50 times to get a shot of an elephant reaching into a bus looking for food. 

Meanwhile in Nepal, drones allowed the team to capture footage of tigers mating and hunting.

Sir David, who has worked for the BBC since 1952, turned 98 while they were making the series. Series producer Matthew Wright revealed that the crew sang happy birthday to the national treasure.

Mr Wright, in words reported by the Daily Mirror, said: 'We said "happy birthday". He was business-like. He said, 'Let's move on. What are we doing next?' 

Producer Mark Wheeler said: 'He's pretty remarkable. The British public look to him as a real authentic voice. He's as enthusiastic as ever.'