Japan’s financial regulator plans to ramp up scrutiny of about $67 billion (¥9.7 trillion) of high-yield loans backed by government bonds and other assets that have become popular among regional banks, according to people familiar with the matter.

At a regular meeting with regional bank executives on Wednesday, a senior official at the Financial Services Agency called on lenders to disclose the amount and market value of their holdings, said the people, who asked not to be named discussing a private matter.

The FSA will review these disclosures and may consider extra actions if necessary, the people said. The watchdog also plans to publish its assessment in a report by year-end, they said.

A spokesperson for the FSA declined to comment.

Repackaged Japanese government bonds (JGB) and other structured loans have drawn the regulator’s ire after some regional banks rapidly ramped up holdings. Officials are concerned the firms may lack proper risk management for the opaque products and could suffer mounting losses if market rates move against them.

These products typically bundle domestic government bonds with derivatives to enhance returns. They have been gaining traction from some banks because the buyers don’t have to mark them to market, thus avoiding the disclosure of paper losses. Holders can also count them as loans, giving the impression of growth in their core lending business.

Senior FSA official Toshinori Yashiki said in an interview in February that the regulator would scrutinize banks that have increased purchases of such products. Brokerages that are actively pitching these products to lenders will also be in the regulator’s crosshairs, he had said.

At least one brokerage, Mitsubishi UFJ Morgan Stanley Securities, stopped selling structured loans, including JGB-backed loans, in May after the regulatory backlash.