ACTPLA says two heritage-listed 1920s cottages have been partially demolished on the site of the development and ''the demolition was not in accordance with the development approval'', leading to the stop-work notice being issued on April 11.

The directorate says it is ''currently considering options available under legislation in relation to compliance of the Heritage, Planning and Development and the Construction Occupations acts.''

However, Ric Butt, a former national president of the Royal Australian Institute of Architects, says that the development is following all approvals yet he has not yet been given an opportunity to argue his case with ACTPLA.

''We're being judged guilty until we prove ourselves innocent,'' he said.

Mr Butt is the architect and owner of one of the blocks in the boutique Westbourne of Yarralumla development, a seven-unit project on the corner of Bentham and Hutchins streets that is incorporating aspects of the original cottages.

The approved plans did allow for partial demolition and reconstruction of the cottages, providing they matched original elements.

A spokeswoman for the Environment and Sustainable Development Directorate said it had had contact with Mr Butt on April 10, 11, 16 and 19 and a meeting with him was scheduled for next Friday, ''which was the earliest date possible to meet given an investigation is currently under way''.

Mr Butt said in the meantime he is losing money on the stalled construction, as was his builder who had a young family.

''I think the real point for me is how can anyone make a frivolous claim, without any evidence or actual and proper information, and ACTPLA responds with a stop notice?'' he said.

Local historian Ann Gugler said she was horrified to see the state of the cottages, one of which was originally occupied by Jeremiah Dillon, a foreman at the sewer works at Weston Creek from 1915 to 1929.

''It was in mint condition and I couldn't sleep after seeing what had been done with it,'' she said.

However, Mr Butt said ''the reality was the buildings were structurally unsound''. He was going to great lengths to preserve the heritage features as outlined in the development approval.

Mr Butt said his professional reputation was, in the meantime, also being threatened and he was wrongly being portrayed as being uninterested in heritage.

He had been trying to develop the site since 1995 and it had been subject to two cases before the ACT Administrative Appeals Tribunal, which ultimately gave him the green light to proceed, saying the development satisfies ''the conservation objectives of the heritage citation'' and that Mr Butt had made ''exhaustive efforts'' to ensure a design ''that complied with the heritage requirements''.

Mr Butt said he was not a large-scale developer and it was ''highly offensive'' to be painted as ''ugly awful people who are trying to do the wrong thing''.