What is the best for Organization is to seprate procurement from Logistic or not?

These both should be separate departments in bigger concerns while when the organization size is small these both can be under umbrella of one head. 

Procurement and Logistics should be handled by different personnel but both should be under the same department head to ensure better coordination

These departments should be separated be it in a large or small organisation;.  Separation or the two will make it easey to design clearly defined policies both on the structure of the organisation and the human capital involved

If the core business in logistics all logistics activities should be in a separate departments, but if the core business is manufacturing or retails business all logistics activities should be under logistics department in this case we can create a committee for procurement, committee members from, logistics department, finance department, production department, internal auditing department, legal department, risk department, and the head of the committee is one of the executive management.

The logistics vice president or manager will be the committee secretary to understand and implement the decisions.