WASHINGTON — Stepping up their efforts against health care fraud, the Obama administration and major insurers announced Thursday they will share raw data and investigative know-how on a scale not previously seen to try to shut off billions of dollars in questionable payments.

At a White House event with insurance executives, Health and Human Services Secretary Kathleen Sebelius said the public-private partnership will allow government programs and the insurance industry to take the high ground against scam artists constantly poking the system for weaknesses.

‘‘Lots of the fraudsters have used our fragmented health care system to their advantage,’’ Sebelius told reporters. ‘‘By sharing information across payers, we can bring this potentially fraudulent activity to light so it can be stopped.’’

State investigators are also part of the effort.

Fraud is an endemic problem plaguing the giant government programs of Medicare and Medicaid and
a headache for private insurers.

But many details of the new partnership have yet to be worked out.

It doesn’t even have a budget, officials said.

However, the goal is to start producing results within a year.

Extensive sharing of claims data will take longer because difficult legal and technical issues have to be worked out.