NEW YORK (Reuters) - Massachusetts' top securities regulator on Thursday issued a regulatory notice to the state's roughly 700 registered investment advisers that if they use robo advisers, they must tell clients and explain the fees charged.

Robo advisers are computer software programs that offer automated investment advice such as suggestions for low-cost funds and computer-generated portfolios, usually at a lower cost than for advice provided by a human adviser.

Robos have boomed in popularity in recent years, and many investment advisers offer clients the option to use a robo adviser for asset allocation in addition to human advice for more complex questions.

The guidance, issued by the Massachusetts' Securities Division, says registered investment advisers must tell clients when they receive services performed by a robo adviser. Advisers also need to tell clients that they can go directly to the robo adviser for services, rather than go through the adviser.

Advisers must also explain the fees that the robos charge, and which investment products and services may not be available through the robo adviser.

The guidance comes amid greater scrutiny of the automated advice industry. In April, Secretary of the Commonwealth William Galvin questioned whether robo advisers can meet the fiduciary standard that human advisers must follow.

"My office has recently raised serious concerns" about robo advisers, Galvin said. "It is vital ... that investors are fully aware of the role robo advisers play in the handling of their accounts and the limitations, restrictions and fees which result."

(Reporting By Elizabeth Dilts; Editing by Steve Orlofsky)