The President of the European Council, Donald Tusk, warned Britain that leaving the EU without any formal agreement will cause the U.K. serious damage.
"I want to explain that the scenario will be bad for both, but primarily for the U.K. because remain a number of unresolved issues," - said Donald Tusk.
"We will not be intimidated by threats, and I can assure you that they just will not work," he added.
British Prime Minister Theresa May has promised to initiate the process of leaving the 28-nation units to the end of the month. Thus, launching two years of negotiations that would permit speed up the country exit early in 2019.
"We have no choice but to start negotiations about U.K. exit," said Tusk. "We would like to make this process constructive and orderly".
This means the elimination of uncertainty of around 3 million EU citizens living in the U.K. and 1 million Britons who lives in the 27 different countries. The main struggle will unfold around money because the U.K. could face €60 billion ($64 billion) Brexit Bill.
The negotiations that would affect the future of Britain's relationship with the EU, should be completed in October 2018 leaving time for European side and the UK for acceptance the final agreement on this issue.