Do you know of an American version?
Private property: Do as they say...
Public property: Tell the cop to f$#k off.

...I don't think any police officer is that unreasonable though. You're not REQUIRED to give any information, unless you're driving a vehicle. Under no circumstances are you required, or the officer is allowed, to delete ANYTHING. And, again, if you're in a public area, and presentable, you do not have to leave.
Still, if a officer asks, I'd say just cooperate. If its 3 in the afternoon, and you're sporting pajamas, turban, and a 3 year old beard next to an airport, I'd stop you too. And they usually have a good reason (security risk or otherwise) for why they don't want you there.
Oh, and keep in mind certain federal agents have the authority to detain you for 48 hours without cause, so don't piss them off.