LONDON (AP) — The European Union said Thursday it is preparing new regulations that could force a key financial market — and potentially thousands of jobs — to move away from London once Britain leaves the bloc.

The EU’s executive Commission said it will present next month new rules on the oversight of this market, the so-called clearing of euro-denominated trades.

In financial markets, clearing is the business of acting as an intermediary in a trade to reduce the risks from defaults by ensuring funds are delivered to the seller. Some 75 percent of euro-denominated interest rate derivatives are cleared in the U.K. — and tens of thousands of jobs depend on the business.

Some European authorities want this euro clearing business to be located in a country in the EU, as the bloc is tightening its oversight of banks and financial services in the wake of the financial crisis.

When asked Thursday whether clearing houses would be forced to leave the U.K. if they wanted to continue handling euro-denominated trades, Commission Vice-President Valdis Dombrovskis said the EU was “looking at this issue.”

“Of course, in a context of Brexit we see that the situation is changing,” Dombrovskis told reporters in Brussels. “The bulk of EU denominated derivatives are cleared in the U.K., and therefore we need to assess what implications it has for financial stability.”

While the Commission did not specify what the new rules would be, it expressed concern that after Brexit a “substantial volume” of euro-denominated transactions would be cleared outside the EU, meaning they would not be subject to the bloc’s regulations and supervision.

The Commission said it wants to ensure clearing houses are subject to the “safeguards provided by the EU legal framework” in areas where they play a key role in the stability of financial markets and monetary policy.

The statement comes as the EU and Britain begin two years of complex negotiations over the separation of two economies that have been intertwined for more than 40 years. A German newspaper reported Sunday that European Commission President Jean-Claude Juncker said Prime Minister Theresa May was in a “different galaxy” in her expectations for Brexit. May yesterday accused EU officials of making “threats” to influence next month’s general election.

Treasury chief Phillip Hammond said Britain would consider any proposed clearing regulations but that the EU must be careful not to disrupt growth and investment in the U.K. and Europe.

“London is the world’s No. 1 financial center, with high standards of financial supervision, including longstanding cooperation with EU institutions,” Hammond said in a statement. “This benefits the entire continent. We trust everyone in the negotiations will see the value in not undermining that.”

TheCityUK, which lobbies on behalf of Britain’s financial services industry, was more blunt.

“A forced re-location of euro-clearing would lead to disruption, uncertainty and fragmentation of the market,” Chief Executive Miles Celic said in a statement. “A potentially less liquid, and less competitive EU market would result in higher costs for European savers and investors. This would ultimately be detrimental to people and businesses in Britain and in Europe. This is in no one’s interest and is entirely avoidable.”