The European Union warned Britain on Wednesday that pulling out of the bloc will be a painful -- and costly -- process with real consequences.
"Some have created the illusion that Brexit would have no material impact on our lives or that negotiations can be concluded quickly and painlessly," the EU's chief negotiator Michel Barnier said Wednesday. "This is not the case."
Barnier's comments came just hours after the Financial Times reported that Britain could face an upfront payment of up to €100 billion ($109 billion) to leave the EU.
That figure is significantly higher than previous divorce bill estimates, but the newspaper cautioned that the net cost would be reduced over the coming decades by reimbursements from the EU.
The eye-popping figure was quickly shot down by U.K. Brexit Secretary David Davis.
"It's gone from €50 billion, to €60 billion to €100 billion," Davis said during a radio interview. "I know that's not where we'll end up."
EU member states pay into a communal budget, which finances infrastructure projects, social programs, scientific research, farm subsidies and pensions for EU bureaucrats. The bloc's budget is negotiated to cover a period of years, with the current agreement extending to 2020.
Negotiators must now determine how much Britain should pay to settle its financial commitments to the EU.
"There is no punishment. There is no 'Brexit bill.' The financial settlement is only about settling the account," Barnier told reporters.
Bruegel, a think tank, has independently calculated that the initial payment by the U.K. could reach €109 billion ($119 billion). However, it estimates the net cost to Britain after repayments would end up between €25 billion ($27 billion) and €65 billion ($71 billion).
Prime Minister Theresa May officially triggered Brexit in March, but formal talks haven't started yet.
Even so, tensions between Britain and the remaining 27 member states of the EU have spiked in recent days. Divisions burst into the open following a meeting last week between May and European Commission President Jean-Claude Juncker.
The EU side reportedly described the discussions as having gone "badly" and British officials as being in a "different galaxy."
May, who is campaigning ahead of next month's U.K. general election, responded by saying she will be a "bloody difficult woman" in talks with the EU.
"The simple truth is: This is going to be a tough negotiation," Davis said Wednesday. "Nobody argues that point."
Barnier warned that the time available to work out the deal was very short.
"The UK's decision to leave the European Union has now caused 10 months of uncertainty," Barnier said. "We need to remove that uncertainty. It is high time to start negotiating. As soon as the U.K. is ready to come to the table, we shall start negotiating. The clock is ticking."