Goldman Sachs International Chairman José Manuel Barroso said he was surprised the U.K. has not put its financial services sector at the forefront of its negotiations over Brexit.

Barroso, a former president of the European Commission, described financial services as the "jewel in the crown" of Britain's economy but said it had not been at the forefront of negotiations regarding the country's exit from the EU.

"I would have expected financial services to be at the top of the U.K.'s agenda over Brexit," he told the City Week conference in London.

Goldman Sachs International is the London-based subsidiary of U.S. investment bank Goldman Sachs Group Inc. The parent company has said it will have two post-Brexit hubs in the EU, in Paris and Frankfurt, and that it may temporarily move portfolio managers to New York in the event of a no-deal Brexit.

Barroso said he expected the City of London to remain one of the world's leading financial centers after Brexit because of its financial market infrastructure, culture and human assets.

But he added that he expected Frankfurt and Paris to benefit as banks moved from London to avoid the uncertainty of Brexit — and he described this flow as "irreversible."

"I continue to believe that London will remain one of the world's leading financial centers, but the City should not underestimate the risks posed by Brexit," Barroso said.

At the same conference on May 20, U.K. Trade Secretary Liam Fox said he was confident Britain's financial services sector would remain a global leader after the country leaves the EU.