Insurers fear the move will reduce practices' ability to fully integrate non-UK-qualified architects into their so-called risk-management systems.
Brussels wants to make it easier for EU architects to work anywhere in member states, including the UK, and is forcing through a major shake-up of the Architects Act 1997 (AJ 28 August).
European Directive 2005/36/EC will effectively remove the legal obligation on architects trained in the European Union to register with the ARB as long as they are working in the UK on a 'temporary or occasional' basis.
This would mean British firms would be forced to automatically recognise overseas architectural qualifications from 20 October this year - a move rubber-stamped by the ARB.
Howden Insurance Brokers (HIB), based in London, accepts the move is likely to help reduce the shortage of trained architects but warn it is causing 'some consternation' amongst UK insurers.
Its head of architects' personal indemnity, Ted Jones, advises architectural firms to take two key steps before hiring temporary or occasional professionals.
He said: 'Firstly, advise a broker to ensure these workers are included and named on the policy.
'Secondly, firms must review their risk-management system and ensure they build in an effective integration procedure to demonstrate the risk-mitigation steps they have taken to their insurer when their policy comes to renewal - and if they have any doubts, contact a specialist PI broker for help and advice.'