French to English Bus/Financial Law: Contract(s) Maintenance Contract

"Le Prestataire s'engage à respecter les consignes de sécurité applicables sur le site qui lui auront été notifiées par le Client et * à autoriser, à tout moment, le passage et l’intervention des prestations de sécurité du Client *."

This is in a contract for the maintenance of specialist machinery, under the terms of which the manufacturer's staff make emergency service calls (ALSO called 'interventions') to the customer's business to repair the machinery installed there. Under this section (Health and Safety) the manufacturer (here referred to as the service provider) agrees to allow the customer's security personnel to have access and, well, basically do their job, at all times. But I am REALLY struggling to put the last bit (the bit between the asterisks) into good English.

At the moment I'm working with something along the following lines: "shall allow/grant/permit the Customer's security personnel access and ?? at all times". I'm thinking this sentence is going to need some serious rejigging to make sense in English. And I hate the French word 'intervention'....

p.s. I am aware that this is a weird use of 'prestations de securité', but I'm relatively sure from the context that it must be the security staff (rather than the services they provide) that are being referred to. Unless anyone would like to argue otherwise? TIA.