WhatsApp, Snapchat and iMessage are at risk of being banned in the UK because the communication services involve the use of encrypted messages.
The UK government, backed by Home Secretary Theresa May, believe messaging apps such as these are a potential threat to security.

British Home Secretary Theresa May
A new law by the name of The Communications Data Bill, also known as The Snooper’s Charter, will mean that the online activity of people using the services will be documented.
The law was blocked in 2013 but with a new government in place, it could be law by 2016.
Earlier this year, UK Prime Minister, David Cameron said: “In our country, do we want to allow a means of communication between people which we cannot read?”

British PM David Cameron
“My answer to that question is no we must not. If I am prime minister, I will make sure it is a comprehensive piece of legislation that makes sure we do not allow terrorists safe spaces to communicate with each other”.
If the law is passed, it would mean that information passed through these services would be stored for up to a year.