IN THE LAST YEAR, there has been a "steady deterioration" of human rights in Pakistan, according to Amnesty International. This has happened even as the United States tightened its security ties to Pakistan. Is there a connection? Not necessarily, but if it is only a coincidence, it is a disturbing one. The administration's main pitch in dealing with repressive governments has been that they would sooner relax internally if their external security requirements were met. The admininistration has also contended that the quiet touch would be rewarded. Where is the evidence in Pakistan?

Last year, Amnesty reports, the military regime in Islamabad jailed thousands for political offenses, and increased its use of torture. In a new turn, President Mohammed Zia ul-Haq effectively annulled the 1973 constitution's guarantees of fundamental rights, leaving individuals virtually defenseless against arbitrary official power. Such consolation as there has been for Pakistan's frequent turns to military rule in its 34 years has lain in its retention of at least a formal commitment to representative government. President Zia has abandoned that commitment. Institutionally speaking, he is now in a free float. Having banned the political parties, he has created in their stead a new federal council whose powers are to be what he says--no more.

Pakistan is scrunched between India, a much larger country with which it has warred three times, and Afghanistan, whose Soviet occupiers have driven upwards of 2 million refugees onto its soil. It has a full Third World set of ethnic, social and economic tensions. A prudent person would have to say its future is uncertain. The Reagan administration has made a certain bet on the Zia regime, which is the stronger for the American investment in one sense but which could end up the weaker if this investment tempts it to shun accommodation with its own people. If this happens, the results would be far worse for Pakistan than for the United States. Perhaps the administration does not feel it is its job to say this to President Zia. All the more reason for him to heed Amnesty.