PORTLAND — Gov. Paul LePage’s administration needs legislative approval to build a secure, privately run facility for patients in state custody with mental illness who no longer need hospital care, the state attorney general said.

Democratic Attorney General Janet Mills sent a letter to the Republican governor’s administration Tuesday. The legislature’s appropriations committee discussed the letter Wednesday during a meeting on the administration’s proposal.

LePage has insisted his administration doesn’t need legislative approval for the proposed $3.5 million facility if it is built outside a specially designated zone in Augusta. He told lawmakers in a letter this month that he started working with legislators to get plans for the 21-bed Augusta facility approved in December but ended such talks to avoid a “gauntlet of legislative kangaroo courts.”

“It is this miserable record that forces me to do everything in my power to remove the Legislature from this process,” he said then.

So LePage scrapped the plan for the facility in Augusta and announced it would instead be built in Bangor.

But in her letter, Mills said some legislative approval is needed to authorize construction of a new state building, no matter where it’s located. A facility outside the special Augusta zone would need the entire legislature’s approval, she said.

Mills said her letter wasn’t an official opinion but rather general comments on a proposal that hasn’t been presented to lawmakers in written detail.

The appropriations committee agreed that if LePage changes his mind and builds the facility in Augusta, a group of legislative leaders that previously blocked the plan should now approve it. Some committee members said they’re not endorsing where the facility’s built, and Republican Sen. Roger Katz said everyone agrees Maine needs the facility.

LePage’s spokeswoman Adrienne Bennett said the governor “will continue to move ahead in a timely fashion to ensure patients are provided a facility in an expedited manner.”

“Democrats have already delayed the process by playing politics and rejecting the Augusta location,” she said in an email. “Now, they want to flip flop their decision when the Administration has moved ahead.”

In response to follow-up questions about the governor’s plans, Bennett said his office will “let you know when there is information to share.”

Legislative leaders have called for public review and more details about the facility, which would be run by a private vendor and house people committed to a mental health facility after facing criminal charges. LePage’s administration says the facility would free up needed psychiatric beds at Riverview Psychiatric Center and help the facility regain federal certification to protect more than $20 million in federal funding.

Representatives of the Department of Health and Human Services said it has the money needed to build the facility.