The firm, which has a major London office, is suing Ghana-based Building Industry Consultants in a row over work on two schemes.
According to a British High Court writ, it says it has not been paid for work as an architect - and civil and structural engineer - for Building Industry Consultants.
Now the firm is seeking unlimited damages of more than £300,000 for breach of contract, or payment of a reasonable sum for its fees, and legal costs.
The practice is also seeking a legal ruling that it retains the copyright in plans and designs prepared for projects in Accra and Kumasi, following Building Industry Consultant's instructions.
All further details of the row remain under wraps due to legal reasons.