Investing.com -- UBS CEO Sergio Ermotti said Wednesday the Swiss bank needs to broaden its business in the United States as he pledged to prepare for any scenario that could emerge from a parliamentary debate on proposed tougher capital rules for the lender.

Speaking in the Swiss city of St. Gallen, Ermotti vowed to work until the last minute to ensure UBS (SIX:UBSG) and Switzerland kept benefiting from each other amid speculation the bank could move its headquarters abroad if it found the new rules too onerous.

UBS secured a national banking license in the United States in March. Ermotti said expanding in the United States did not necessarily need to be via an acquisition.

"We may have to do an acquisition. We may want to do an acquisition," he said at the St. Gallen Symposium. "I don't know about any big organization that can rule out acquisitions."

The government sent a bill to parliament last month that would make foreign expansion dearer for UBS. Swiss lawmakers decided Monday to review alternative options for the proposed new capital rules, putting off a swift decision on the matter.

Lawmakers are due to continue debating the capital bill in August, likely meaning it will not face a vote by the full upper chamber of parliament before September.

"I'm focused on one option, making UBS strong out of Switzerland," Ermotti said, adding the bank has a fiduciary duty to prepare for any scenario.