The text of President Reagan's letter Tuesday to federal employes about disclosure of classified information:

Recent unauthorized disclosures of classified information concerning our diplomatic, military and intelligence activities threaten our ability to carry out national security policy. I have issued a directive detailing procedures to curb these disclosures and to streamline procedures for investigating them.

However, unauthorized disclosures are so harmful to our national security that I wish to underscore to each of you the seriousness with which I view them.

The unauthorized disclosure of our nation's classified information by those entrusted with its protection is improper, unethical and plain wrong. This kind of unauthorized disclosure is more than a so-called "leak"--it is illegal.

The attorney general has been asked to investigate a number of recent such disclosures of classified information. Let me make it clear that we intend to take appropriate administrative action against any federal employe found to have engaged in unauthorized disclosure of classified information, regardless of rank or position. Where circumstances warrant, cases will also be referred for criminal prosecution.

The American people have placed a special trust and confidence in each of us to protect their property with which we are entrusted, including classified information. They expect us to protect fully the national security secrets used to protect them in a dangerous and difficult world.

All of us have taken an oath faithfully to discharge our duties as public servants, an oath that is violated when unauthorized disclosures of classified information are made.

Secrecy in national security matters is a necessity in this world. Each of us, as we carry out our individual duties, recognizes that certain matters require confidentiality. We must be able to carry out diplomacy with friends and foes on a confidential basis; peace often quite literally depends on it--and this includes our efforts to reduce the threat of nuclear war.

We must also be able to protect our military forces from present or potential adversaries. From the time of the Founding Fathers, we have accepted the need to protect military secrets.

Nuclear dangers, terrorism and aggression similarly demand that we must be able to gather intelligence information about these dangers--and our sources of this information must be protected if we are to continue to receive it. Even in peacetime, lives depend on our ability to keep certain matters secret.

As public servants, we have no legitimate excuse for resorting to these unauthorized disclosures. There are other means available to express ourselves:

* We make every effort to keep the Congress and the people informed about national security policies and actions. Only a fraction of information concerning national security policy must be classified.

* We have mechanisms for presenting alternative views and opinions within our government.

* Established procedures exist for declassifying material and for downgrading information that may be overclassified.

* Workable procedures also exist for reporting wrongdoing or illegalities, both to the appropriate executive branch offices and to the Congress.

Finally, each of us has the right to leave our position of trust and criticize our government and its policies, if that is what our conscience dictates. What we do not have is the right to damage our country by giving away its necessary secrets.

We are as a nation an open and trusting people, with a proud tradition of free speech, robust debate and the right to disagree strongly over all national policies. No one would discipline people who understand the need for responsible action.

As servants of the people, we in the federal government must understand the duty we have to those who place their trust in us. I ask each of you to join me in redoubling our efforts to protect that trust.