Some months ago several of my employees were involved in a road accident in a company vehicle during working time. The insurers of the other vehicle are proposing to pay them only the difference between their normal earnings and their sick pay. This means I will have borne most of the cost of the accident through the sick pay I have had to pay out.
Unless there is a clause in your employees contracts of employment catering for this eventuality you will not be able to recover the money. You need to stipulate that monies advanced during absence caused by the actions of a third party must be reimbursed where compensation is claimed. The insurers would then be obliged to reimburse your employees for the amount they were liable to reimburse you. It is now fairly common in industry for this clause to appear.