PLANNERS have ordered work on the Castle Hill Hotel to stop.
The owners, the Thandi Partnership, have been served with a stop notice which took effect at the weekend.
An enforcement notice has also been served on the building, which was one of Huddersfield's best-known landmarks.
And it could mean that the new building under construction will have to be demolished.
Work began to refurbish and extend the Victorian hotel and pub last year after the building had been shut for more than a year.
Permission had been given by Kirklees Council to extend and alter the original building and re-use much of the original stone and roofing material for the rebuild.
But Kirklees Council planning officer Bill Topping said the building now taking shape on the hilltop did not appear to have been built in accordance with the approved plans.
He said the floor area, height and cellar area were all much larger than was agreed.
And he said the old building had been completely knocked down and something new, not an extension, had been built.
He said the Thandi Partnership had been advised several weeks ago that the project was not going as planned, but work had continued.
Mr Topping said planning officers had no option but to serve a stop notice and enforcement notice.
Letters of complaint had also been received from Huddersfield Civic Society and several members of the public.
The Partnership has the right to appeal to the Department of the Environment about the notices and a planning appeal would then be held.
If proved in the council's favour, the building could have to be demolished and the project re-started to comply with planning permission.
Mr Alistair Ingram, agent for the Thandi Partnership, said he had no comment to make at this stage.
* A hotel has stood on Castle Hill since 1812.
* The nearby Jubilee Tower, which is unaffected by any development, was put up in 1898 to commemorate Queen Victoria's diamond jubilee the year before.
* Castle Hill is the site of an Iron Age fort and designated as a scheduled monument.
* The owners had to work with English Heritage and the West Yorkshire Archaeological Service on the demolition.
* An archaeologist needed to be on site during all excavation work.