WhatsApp said on Tuesday a security breach on its messaging app had signs of coming from a government using surveillance technology developed by a private company and may have targeted human rights groups.

Facebook Inc said it restored services on Sunday after some users could not access its social networking site, photo-sharing network Instagram and messaging app WhatsApp.

Facebook Inc's WhatsApp messenger service is globally limiting the number of times a user can forward a message to five, in a bid to fight ‘misinformation and rumours’, company executives said on Monday.

Indian police said Tuesday that 10 people had been arrested over the murder of a man accused of kidnapping children in the latest lynching linked to rumours circulating on WhatsApp.

The messages will be charged at a fixed rate for confirmed delivery, ranging from 0.5 cents to 9 cents per message depending on the country, WhatsApp said.

More than 20 people have been killed in similar incidents in India in the past two months.

WhatsApp announced curbs on its service in India on Friday in an effort to stop a spate of horrific lynchings and to assuage government threats of legal action in its biggest market.

The Facebook-owned messaging service has been under immense pressure to curb the spread of misinformation in India.

The assaults in Gujarat, sparked by talk of hundreds of child kidnappers on the loose, are just the latest in a string of similar recent episodes in at least five Indian states.

WhatsApp has raised its minimum age for users in the European Union to 16 years, as the bloc prepares for a new online privacy law to come into force next month.

Police have questioned 45 people, including students and tutors, over the leak but no arrests have been announced.

Some of the violence was instigated by postings on Facebook threatening more attacks on Muslims, according to the government, which on March 7 cut access to Facebook, Viber and WhatsApp.