In the wake of a major controversy over changes to user rules, WhatsApp is recommitting itself to full encryption and holding out the prospect of new features to protect user privacy.

These include the possibility of sending messages that can only be viewed once by the recipient. This could be useful, for example, if you need to send a password to family members, WhatsApp boss Will Cathcart says.

It will also be possible to set chats to disappear on their own after a certain time. People on the whole don't want their messages to stay forever, Cathcart argues, pointing out that we don't carry a recording device with us when we talk.

The Facebook-owned company has launched an ad campaign for radio, TV and billboards aimed at improving its reputation in privacy.

In the UK and Germany, key markets in Europe, short promotional videos will say that content sent on WhatsApp is only visible in plain text to the users involved, thanks to end-to-end encryption.

WhatsApp has more than 2 billion users. In recent months, however, the service has had to contend with criticism and an exodus of users following the announcement of new usage rules which came into force in mid-May.

The planned changes to the rules sparked outrage on social media, when many interpreted them as saying that more data would be shared with parent company Facebook.

WhatsApp rejected this as a misunderstanding and repeatedly stressed that the end-to-end encryption, with which the service itself also has no access to content, would not be changed.

However the damage control could not stop users switching to other messaging apps, and rivals like Telegram and Signal noted record user sign-ups in the wake of the scandal.

Many users meanwhile became more aware that WhatsApp collects information about how they use their phone and where they are - information that could be used to let its parent company Facebook create a better picture of them for advertising.

WhatsApp chief Cathcart acknowledges mistakes were made in announcing the new rules. "We need to communicate clearly what we are doing and why," he says, admitting that WhatsApp only became clearer once "the confusion" took place. "That's on us."

He says WhatsApp had planned an advertising campaign for end-to-end encryption before the recent backlash, but after the controversy in recent months, WhatsApp has even more reason to talk about it.

In the meantime, an overwhelming majority of users who had already been asked for their consent to the new rules had accepted them, Cathcart says.

He did not give exact figures. Originally, users who did not agree to the new rules were supposed to lose access to basic functions over time. In the meantime, they no longer face any consequences.

Only the new functions for communicating with companies can be used after agreeing to the update. According to WhatsApp, they were the central reason for the change in the terms of use.

Cathcart criticises that some governments have been trying to soften encryption in chat services, and hopes over time governments will realise that the most important role they can play is to provide more security by standards for businesses.

WhatsApp argues to governments that end-to-end encryption helps protect citizens' security. Facebook remains committed to its plan to bring full encryption to its second chat service, Messenger, as the next step, Cathcart said.

In several countries, attempts are underway by governments and authorities to undermine full encryption in chat services such as WhatsApp, while government bodies in many countries are able to monitor traditional SMS messages.

Government security officials meanwhile say that locking them out of all online communications prevents them from monitoring the activities of criminals and extremists.

Recently, however, international police authorities succeeded in striking a major blow against organised crime with the help of a chat app, of all things, after investigators succeeded in establishing their allegedly secure app as a communication channel in criminal circles.

 - dpa