WhatsApp could see itself no longer being allowed in the UK, the app's boss has warned.
Boss Will Cathcart, said the new Online Safety Bill may have serious consequences for millions of users in the UK.
He claims the new bill will see end-to-end encryption that WhatsApp uses weakened - which prevents messages from being spied on.
Currently, the messages sent on the app are only able to be read by you and the person you're texting.
But under the new bill, WhatsApp would have to give up this encryption to allow authorities to check on users' messages for 'illegal content', he said.
However, Mr Cathcart has warned WhatsApp would not allow the UK government to do this - and may remove its services from the UK entirely.
He said: "Our users all around the world want security—98% of our users are outside the UK, they do not want us to lower the security of the product.
"We won't lower the security of WhatsApp. We have never done that—and we have accepted being blocked in other parts of the world."
WhatsApp competitor app Signal has also called out the UK government for the controversial new bill and stated it "poised to undermine encryption and create a regime of mass surveillance".
However, the UK government has denied the claims it wants to ban end-to-end encryption.
The government told the BBC: "The Online Safety Bill does not represent a ban on end-to-end encryption. It is not a choice between privacy or child safety—we can and we must have both."
But the Information Commissioner's Office has announced that measures to weaken encryption are necessary for the greater good.
It said: "Where less intrusive measures are available, they should be used," and added that it supports "technological solutions that facilitate the detection of illegal content without undermining privacy protections for everyone."