Employers and controllers of premises have obligations based on the extent of their control.
A controller of premises must identify any foreseeable hazard arising from the premises, which includes the potential to harm the health and safety of any person using, accessing or egressing (exiting) the premises.
The controller must assess the risk of harm arising from this hazard and eliminate any risk.
An employer has a general duty of care to provide a safe workplace. That duty includes ensuring that any premises controlled by the employer (including the means of access to or exit) are safe and without risks to health and safety.
The issue of responsibility for dealing with a health and safety issue relating to access and egress to a workplace will depend upon who has control of access and egress.