The group of 25 ex-staff at the firm, which was founded in Edinburgh almost 60 years ago, say they are owed more than HK$3 million (£236,000) in pay.
They have now gained the support of a member of the legislative council of Hong Kong in pursuing the former British colony’s labour department to investigate the allegations and potentially prosecute company directors.
According to Hong Kong employment law, failure to pay wages and failure to comply with a tribunal order constitutes a criminal offence, with those convicted facing fines or even imprisonment.
It is understood that during a meeting held on Saturday in Hong Kong, legislative council member Lee Cheuk Yan showed his support for the claimants.
A spokeswoman for the former employees said that all those affected had followed the correct procedures and filed claims with the local labour department and labour tribunal.
While RMJM has agreed the sums claimed and the tribunal has awarded payment orders, no money has been forthcoming, the spokeswoman added.
It marks the latest blow to a firm which has seen its headcount shrink from more than 1,200 at the end of the last decade to a few hundred amid redundancies and walkouts over claims of unpaid wages.
Last year, the company said it was moving its head office from Edinburgh to Dubai, to focus on its international business, insisting it had never seen itself as a Scottish firm.
At the time, managing director Declan Thompson admitted the company was still behind with salary and redundancy payments, but added that neither chief executive Peter Morrison nor his father Sir Fraser Morrison, who bought the company ten years previously, had received a salary for more than 18 months.
Thompson said RMJM was likely to retain an official registration in Scotland in name only. As part of changes earlier in 2013, the firm had axed 40 posts from its offices in Edinburgh, Glasgow and London.
The new business would be run by Scot Harry Downie, who works from one of the company’s offices in the Middle East.
Thompson told The Scotsman last June: “People always talk about RMJM being a Scottish firm and there are a lot of positive things about that, but we have never really seen ourselves as Scottish.
“Scottish roots, Scottish ownership – great. But we are an international practice. We didn’t see the Edinburgh heritage as an issue.”
RMJM was behind a number of Scottish landmarks including the parliament building at Holyrood, while overseas projects have included the Beijing Olympic convention centre.
The Hong Kong operation is registered with Peter Morrison and Thompson as company directors and Nick Haston serving as managing director.
The case of unpaid salaries at the office is said to be “unprecedented”, according to a press release issued on behalf of the former staff.
It is said that in the second quarter of 2013 alone, 50 cases of delayed pay were registered at the Hong Kong labour department and to date the 25 ex-employees are waiting to receive a total of HK$3.37m in outstanding wages.
A spokesman for RMJM told The Scotsman: “These are matters which are and will continue to be dealt with by our lawyers.
“It would be inappropriate to comment on the specifics of the press release by former employees other than to say the facts and circumstances are not as set out in the release and the matter will be resolved appropriately and in accordance with local laws.”