PARIS (AFP) - Researchers at an Israeli cyber-security firm said they had found a flaw in WhatsApp that could allow hackers to modify and send fake messages in the popular social messaging app.

CheckPoint said on Wednesday (Aug 8) the vulnerability gives a hacker the possibility "to intercept and manipulate messages sent by those in a group or private conversation" as well as "create and spread misinformation".

The report of the flaw comes as the Facebook-owned company is coming under increasing scrutiny as a means of spreading misinformation due to its popularity and convenience for forwarding messages to groups.

Last month, the app announced limits of forwarding messages following threats by the Indian government to take action after more than 20 people were butchered by crazed mobs after being accused of child kidnapping and other crimes in viral messages circulated wildly on WhatsApp.

WhatsApp said in a statement: "We carefully reviewed this issue and it's the equivalent of altering an e-mail to make it look like something a person never wrote."

However, WhatsApp said: "This claim has nothing to do with the security of end-to-end encryption, which ensures only the sender and recipient can read messages sent on WhatsApp."

The app noted it recently placed a limit on forwarding content, added a label to forwarded messages, and made a series of changes to group chats in order to tackle the challenge of misinformation.

Founded in 2009 and purchased by Facebook in 2014, WhatsApp said that at the beginning of the year, it had more than 1.5 billion users who exchanged 65 billion messages per day.