ściśle poufne

I expect you all to keep this most strictly confidential.

What I am about to tell you is strictly confidential.

You must know, of course, our client data is strictly confidential.

"You must keep the matter strictly confidential," said the doctor.

Your work for me would be strictly confidential, of course.

Of course, my call to the manager was strictly confidential, but he is one person who might expect you to be here.

And I thought news of that new planet was to be strictly confidential.

The Committee therefore meets in camera and its reports are strictly confidential.

Your meetings with the social work team will be strictly confidential.

The "strictly confidential" information was sitting there, hers for the taking.