IR35 status of workers outside the UK

Dear all

We have a number of contractors (UK Limited companies all) working in the EEA for an overseas client and undertaking all work outside of the UK. Their contracts specifiy the place of work as the client office. Despite having  listened in to various webinars and looking at the numerous HMRC publications and notices, we are struggling to understand if on this particular contract they will be exempt from the IR35 legislation. We understand that they are UK workers and tax residents so as soon as they  leave this contract and go to work in a UK based office they would have to be assessed, but we can't find any guidance as to whether this specific contract is exempt. We as the agency are the fee payer, and are UK based - so chain is Client (overseas), Agency (UK), worker (UK Ltd Co, but undertaking all work overseas.) 

Any advice appreciated.