The UK could be facing a Brexit bill from the European Union of up to 100 billion euro (£84.5bn), it has been reported.
It had been believed Brussels was seeking a "divorce deal" of up to 60 billion euro (£50.7bn), but added demands by the EU could send the figure soaring, according to the Financial Times.
The UK could receive calls to contribute to post-Brexit farming payments and may be blocked from obtaining a share of EU assets, the FT said.
The EU will also not allow Prime Minister Theresa May to negotiate Brexit directly with her European counterparts, according to The Times.
The PM would be prevented from joining Brexit discussions at future EU heads of government meetings, the newspaper said.
The only person Mrs May will be allowed to hold such meetings with will be the European Commission's lead Brexit negotiator, Michel Barnier, The Times said.
Such a move would run contrary to Mrs May's claim that she would be negotiating directly on the terms of Brexit with fellow European leaders.
After reports that a meeting between Mrs May and European Commission president Jean-Claude Juncker in Downing Street last week had seen tense moments, the PM appeared to toughen her stance.
Mrs May boasted about being a "bloody difficult woman" after she dismissed "a lot" of the leaked account of the dinner with Mr Juncker as "Brussels gossip".
The Prime Minister told the BBC: "During the Conservative Party leadership campaign I was described by one of my colleagues as a bloody difficult woman.
"And I said at the time the next person to find that out will be Jean-Claude Juncker."
Tory MP Sir Bill Cash told the Daily Telegraph he believed Germany and the EU were trying to influence the election, saying: "What they are doing is trying to exploit a new kind of project fear and that is not going to work on the British people."
Brexit looks likely to again be a major political talking point in the election campaign as Mr Barnier gives a press conference on Wednesday.