The executive director of the national inquiry into missing and murdered Indigenous women and girls has left her post.

The inquiry confirmed Debbie Reid's departure in a statement on Thursday but said it could not discuss the details.

This is another sad day for the families. — Arlen Dumas, Assembly of Manitoba Chiefs

"While we cannot discuss the details of the matter, we thank Reid for her contributions," the statement said.

Reid was hired in October but fell into controversy after the leaking of her introductory email to staff, which stated their primary role was to protect the inquiry's commissioners from "criticism or surprises."

Laurie Odjick, a member of the National Family Advisory Circle, said she learned of Reid's departure in an email from the inquiry earlier in the day.

"I don't even know the best words to describe how I feel right now," said Odjick, whose daughter went missing in 2008.

"So much has happened and families are being left out, and I just don't know any more."

Crown-Indigenous Relations and Northern Affairs Minister Carolyn Bennett expressed 'concern' over high staff turnover at inquiry. (Adrian Wyld/Canadian Press)

The inquiry has been hit by a number of high-profile departures, including one commissioner and a previous executive director.

Crown-Indigenous Relations Minister Carolyn Bennett issued a statement following Reid's departure, saying she was "concerned about the amount of turnover at the commission." Bennett said she was worried it would "distract" from the inquiry's work.

"While we share families' concerns about the difficulties we have seen — the independence of the Commission is crucial and we aren't going to interfere in internal matters," said the statement.

Meanwhile, Arlen Dumas, grand chief of the Assembly of Manitoba Chiefs, repeated his calls for the removal of the existing commissioners, a complete reset of the inquiry and the appointment of a Manitoba-specific commissioner.

Assembly of Manitoba Chiefs Grand Chief Arlen Dumas repeated his call for a full reset of national inquiry. (CBC)

"The inquiry has been plagued with staffing issues almost from the beginning," said Dumas, in the statement. "This is another sad day for the families of our missing and murdered Indigenous women and girls."

The inquiry is scheduled to hold hearings in Yellowknife on Jan. 23 and Rankin Inlet, Nunavut, on Feb. 20.

The inquiry's mandate ends in December.

Inquiry Chief Commissioner Marion Buller has said she plans to ask the federal government for an extension to properly complete the inquiry's work.

Bennett has said she is open to the idea, but needs to see a thorough proposal before making any final decisions.

The inquiry said director of operations Calvin Wong will act as interim executive director.

Josie Nepinak is the executive director of the Awo Taan Healing Lodge in Calgary — a shelter for Indigenous women and their children — and two of her female relatives were murdered.

She said she's not surprised by the latest departure from the inquiry.

"I believe that this resignation puts the inquiry further into a crisis situation," she said.

"It's time for Minister Bennett to intervene and to investigate what is happening internally and to fix that so that it can go forward, because it's the families that are missing out."