Slovakia's Prime Minister has claimed Europe will make sure leaving the European Union is "very painful" for the UK.
Robert Fico said Britain would not be allowed to make EU workers "second-class citizens" while still receiving the benefits of the single market.
He told Financial Times: "It will be very difficult for the UK, very difficult.
"The EU will take this opportunity to show the public: ‘listen guys, now you will see why it is important to stay in the EU’. This will be the position."
Mr Fico stressed he had personal "respect" for Theresa May but said he did not envy her dilemma.
He added: "What would you say if you were in their position? Even if it is the fifth-biggest economy in the world — I understand their financial importance — this will still be very painful for the UK.
"They are bluffing. If you were in their position you would say the same. ‘It will all be fine, it will be fantastic, you will see’.”
“No, no, no, no."
Slovakia's main demand will be "equal treatment" for its citizens in Britain alongside UK workers, Mr Fico said.
He spoke about the "nervousness and fear" in Eastern Europe over Ms May's free movement demand.
Prime Minister Theresa May has so far refused to guarantee the status of EU nationals in the UK, but insisted she wants them to stay after Brexit - if the rights of Britons overseas are respected.
There are currently more than 1 million Eastern European workers in the UK taking advantage of EU residence rights.
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