(CNN) New York's banking regulator has asked Deutsche Bank and two other small lenders about their financial relationships with Jared Kushner, his family members and the family's real estate business, according to a person familiar with the matter.

The Department of Financial Services, the New York regulator, sent a letter last week to Deutsche Bank, Signature Bank and New York Community Bank seeking information about financial arrangements, such as loans and lines of credit, with the Kushner Companies and the family members, the source said.

The regulator, which oversees the safety of New York banks, has asked whether there are any personal guarantees by Jared Kushner on the financing arrangements, to understand the banks' risk if there is a default and the Kushners are unable to pay. The letter is also seeking information about whether any collateral was provided to secure the loans, this source added.

The request by Maria Vullo, the superintendent of the Department of Financial Services, follows an updated financial disclosure form by Kushner revealing new debt and uncertainty over the future of 666 Fifth Avenue, the heavily indebted Manhattan office tower. Earlier this month Vornado, the co-investor on the property, indicated plans to sell its stake.

Read More