With a recent report suggesting advertisers will spend over $1 billion on podcast advertising by 2021, audio streaming rivals Spotify and Apple are going to war.

The two companies already have a frosty relationship, after Spotify recently made an official complaint to the EU earlier this year accusing Apple of leveraging its App Store to disadvantage competitors.

And now the relationship looks poised to go from bad to worse, after Bloomberg reported Apple is looking to buy exclusive rights to podcasts.

It was reported that meetings have taken place between Apple executives and representatives from certain media companies.

Apple has previously taken a neutral approach to podcast content, with its Apple Podcasts app currently facilitating between 50 to 70 per cent of all podcast listening.

However, the company has recently placed a stronger emphasis on services and exclusive content, as sales in iPhones begin to wane.

Apple currently does not charge podcasters to use the software or run any of its own advertising on Apple Podcasts, meaning the service brings the company no financial value.

Music streaming rival Spotify is also showing a growing interest in podcasting in a bid to break up Apple’s dominance, after launching Spotify for Podcasters last year.

It has since spent about $US400 million on acquiring podcasting companies such as Gimlet Media and Anchor and funded original shows from comedian Amy Schumer, journalist Jemele Hill and hip-hop artist Joe Budden.

The interest of the tech giants in podcasting is well-founded, with sales in podcasting having grown 65 per cent yearly for the past three years and the number of monthly listeners doubling over five years, according to the IAB.

In Australia, PwC recently revealed 20 per cent of media buyers regularly bought podcast advertising in 2018 (up from 14 per cent in 2017), four in ten buyers experimented with podcast ads in 2018, and an additional 28 per cent are looking to try for the first time this year.

There has also been a local increase in the number of agencies using programmatic buying for audio and this is expected to increase further this year.