WhatsApp, the Facebook-owned messaging service, is dropping its 1 US dollar (69p) annual subscription fee to go free for all users, the company's chief executive has confirmed.

Speaking at a conference in Germany, WhatsApp chief Jan Koum said the annual fee would be scrapped immediately, and the service would become completely free to all users. Previously the app had been free for the first year before users were asked to pay for every subsequent year.

The charge was introduced after the app became free to download, with long-term iOS users who had paid for the app earlier in its life exempt from the charge as a thanks for paying for it in the first place.

WhatsApp also confirmed that the removal of fees does not mean they are introducing ads to the service, with Mr Koum instead saying the app will look to monetise through businesses communicating with individuals.

"That could mean communicating with your bank about whether a recent transaction was fraudulent, or with an airline about a delayed flight," said WhatsApp in an accompanying blogpost.

"We all get these messages elsewhere today - through text messages and phone calls - so we want to test new tools to make this easier to do on WhatsApp, while still giving you an experience without third-party ads and spam."

Facebook bought WhatsApp for 19 billion US dollars (£13.2 billion) in 2014, and says the subscription fee has harmed growth in developing countries, where the app has become hugely popular.

"As we've grown, we've found that this approach hasn't worked well," the blogpost said.

"Many WhatsApp users don't have a debit or credit card number and they worried they'd lose access to their friends and family after their first year. So over the next several weeks, we'll remove fees from the different versions of our app and WhatsApp will no longer charge you for our service."

There was outcry recently in Brazil when a court briefly banned the messaging app in the country - which is used by millions as a cheap way to communicate with family overseas.