There appear to be two issues in your post. One is that staff members extend their lunch break and another is that they go out to take lunch. While former could be against the rules of the company, latter need not be. Why company should bother where staff members take their lunch? As long as they adhere to the timing of the lunch break, company should not have any objection.
Few staff members may would like to go outside during lunch break. Outside atmosphere could invigorate them. Therefore, whether to take lunch within the company premises or to go out should be left to individual's choice. However, for delayed reporting for duties after lunch break, you may issue circular for initiating strict disciplinary action.
From India, Bangalore
I opine that as an organization you should not go in to the sensitive issues like prayer because it leads to further implications like a demand for prayer room etc., extending to Hindu / Muslim / Christian because I personally observed this in a PSU at Hyderabad hence the break time One hour is lunch time.
Either the employees have it in side or out side is left to them and the organization is concerned with the timing. In case employee going out then the security should ensure that they should enter the entry & exit time in the employee movement register and to submit to HR on daily basis. In case of violations then you need to display a notice with the details. In my opinion only 10 % are culprits, closely monitor and if the scenario repeating even after the notice then initiate disciplinary process, failing which they will take it granted and there is a possibility of some more employees to follow.
From India, Hyderabad
Your want is to adhere strict discipline and the time frame, do you feel adhering time frame and discipline increase product/service? On the agenda what is your real issue? Is it adhering discipline? or You want to increase productivity?
First find out you and your company/organisation the problem behind the issue. In case it is the hour of lunch break is the issue, better, open a canteen and give lunch in a subsidised way, none go outside for lunch. Make the working place admirable and never make it a place of horror.
Have a good day ....
From India, Arcot
This situation requires more open discussion among them and situation would become better over a period of time rather than overnight. Apart from discussion, external agencies / consultant should also be involved in this situation to share their feedback both to employees and management.
Small small initiatives like Happy Hour in office, Birthday Celebrations, Rewards and recognition, Star of the month/qtr, Some value awards etc need to be given.
Regular Team lunch/Dinner needs to be planned.
From India, New Delhi