Scottish politicians have appointed the consultancy to check up on Arup's increasingly fraught inquiry into the incident at RMJM and Enric Miralles' landmark earlier this month.
Meanwhile, pressure continues to mount between Arup and the architects, with RMJM appearing to point the finger of blame at the structural engineer.
RMJM design director Paul Stallan responded to reports by the AJ's stablemate New Civil Engineerthat there was a 'fundamental flaw' with the building's roof by claiming that it was an 'engineering issue'.
He said: 'Arup have got to look at it.'
The comment will come as a massive blow to Arup, the engineer at the centre of the row over the 'wobbly' Millennium Bridge, which was finally completed two years behind schedule.
A spokesperson for the Scottish Parliament said: 'We are in the hands of the structural engineers, and must be guided by them.
'Arup's work is being scrutinised by our independent experts Atkins to ensure that we have the benefit of an impartial second opinion on every step of the process.'
Arup is expected to brief MSPs on the progress of its investigations later today (Friday).