FRANKFURT—European Bank President Mario Draghi said on Monday that the eurozone's economy had so far proven resilient to Britain's vote to leave the European Union, but he warned that economic risks remained and said the ECB stood ready to boost its stimulus again to support growth.

"The extent to which the economic outlook will be affected [by the Brexit vote] depends on the timing, development and final outcome of the upcoming negotiations," Mr. Draghi told European lawmakers in Brussels at a quarterly hearing.

While the eurozone appears so far to have weathered the initial impact of the U.K. vote, Mr. Draghi warned of a "substantial weakening" in the prospects for overseas demand since June, which he said would likely damp export growth.

He stressed that the ECB would "do its part" by preserving its "very substantial" stimulus, and stood ready to act again using all its tools.

He also repeated his call for other policy actors, notably governments, to help out the ECB by carrying out economic reforms.

"Widespread feelings of insecurity, including economic insecurity, remain a major concern," Mr. Draghi said.

The ECB President also defended ultralow interest rates, which have come under increasing fire in Germany, the bloc's biggest economy.

"Low rates are a symptom of the underlying economic situation," Mr. Draghi said. "They reflect weak long-term growth trends and the protracted macroeconomic slump that has resulted from the crisis."

Write to Tom Fairless at tom.fairless@wsj.com and Todd Buell at todd.buell@wsj.com

(END) Dow Jones Newswires

September 26, 2016 11:15 ET (15:15 GMT)