LONDON — A Belgian magistrate judge is investigating whether the Swiss bank UBS engaged in fraud, money laundering and other crimes in an effort to help wealthy individuals avoid taxes, the Brussels prosecutor’s office said on Friday.

UBS is suspected of having directly approached Belgian customers, without going through its Belgian subsidiary, to encourage clients to engage in transactions meant to evade taxes.

UBS acknowledged the inquiry, but it said little more.

“We take note of various articles in the press, which indicate that an official investigation will be conducted,” a UBS spokesman said. “UBS will continue to defend itself against any unfounded allegations.”

The judicial inquiry came after the Belgian authorities said that they had received “excellent cooperation” from the authorities in France, which has conducted a similar inquiry into UBS’s activities.