EU President Donald Tusk on Tuesday unveiled key proposals to keep Britain in the bloc, including a brake on benefit payments for migrant workers and protection for countries that do not use the euro currency.

"To be, or not to be together, that is the question... My proposal for a new settlement for #UKinEU," Tusk tweeted as he published the plan ahead of a crucial summit on February 18-19 when EU states will try for an overall deal with Cameron.