One of the co-founders of messaging app WhatsApp has quit the company following reported disagreements over privacy with parent company Facebook.

Jan Koum, a Ukrainian immigrant who founded WhatsApp in 2009 with Brian Acton, wrote in a Facebook post that “it is time for me to move on”.

“It’s been almost a decade since Brian and I started WhatsApp, and it’s been an amazing journey with some of the best people,” he wrote.

“I've been blessed to work with such an incredibly small team and see how a crazy amount of focus can produce an app used by so many people all over the world.”

Facebook bought WhatsApp in 2014 for $19 billion. At that time, Koum spoke about how he had grown up in fear of the KGB secret police in the former Soviet Union and how that motivated him to build a secure encrypted communication platform.

Facebook CEO Mark Zuckerberg praised Koum with a comment on the post which announced his departure.

“I'm grateful for everything you've done to help connect the world, and for everything you've taught me, including about encryption and its ability to take power from centralised systems and put it back in people's hands,” he wrote.

“Those values will always be at the heart of WhatsApp.”

According to the Washington Post, WhatsApp, which has more than a billion daily users but does not feature advertising, has clashed with social media giant Facebook over attempts to use its personal data to develop products and target ads, as well as weaken its encryption.

Acton himself shared a #DeleteFacebook hashtag after the parent company’s recent Cambridge Analytica data-sharing scandal. He has left the company to start a foundation.