Ms Harte said it had become impossible to carry out her duties

Miriam Harte has headed the County Durham museum, which recreates life during the early 19th and 20th Centuries, since 2001.

In a statement, she blamed "current structures and management arrangements" for her decision.

Durham North MP Kevan Jones described Ms Harte's resignation as bad news for Beamish and the wider region.

The 300-acre site, near Stanley, includes recreations of towns, farms, shops, railway stations and a tram system, as they appeared in 1825 or 1913.

Since her appointment Beamish has opened several major attractions and won the National Tourism Agency's "England for Excellence" Gold Award.

Ms Harte said: "I look back with immense pride on my six years at Beamish. I am especially proud of the development of the organisation and the many national awards the museum has achieved during that time."

"However, despite many efforts to raise and address key issues, I now believe that it is impossible for me to properly discharge the duties of the director of this organisation

Approximately 350,000 people visit Beamish each year

"This is because of current structures and management arrangements, and the way in which these are exercised."

Durham North MP Kevan Jones said: "As a big supporter of Beamish I'm concerned to hear about Miriam's resignation.

"It's bad news for the museum and the region and I would urge the authorities to examine the reasons behind her decision and to react accordingly, not bury their heads in the sand.

"It's problematic that such a nationally-recognised director could resign so suddenly."

Beamish, which attracts about 350,000 visitors annually, is governed by a joint committee of councillors from across the North East.

A statement from Sunderland City Council, which supplies HR advice to the joint committee, said: "We can confirm that Miriam Harte's resignation has been accepted.

"She is currently serving an agreed term of notice and we thank her for her contribution to Beamish over the last six years.

"While she has expressed her personal views publicly, we feel it is not in either her interest or the interest of the museum to comment further at this stage."