The 25th anniversary of the 1963 Partial Test Ban Treaty, which President John F. Kennedy hoped would "check the spiraling arms race in one of its most dangerous areas," arrived Friday with arms control groups pressing for a complete halt to all nuclear weapons testing.

The International Physicians for the Prevention of Nuclear War, a Cambridge, Mass., group that won the Nobel Peace Prize in 1985, said its worldwide chapters would hold special conferences, rallies and speeches to focus attention on the need for a complete ban on nuclear weapons tests.The Partial Test Ban Treaty, signed by the United States and the Soviet Union on Aug. 5, 1963, and eventually endorsed by 115 nations, banned nuclear explosions in the atmosphere, space and sea, but not underground.

There have been some 1,400 underground tests since then, the large majority by the United States and Soviet Union. Only France and China were still testing in the air at the time and did not sign the treaty.

The present comprehensive test ban talks in Geneva have been deadlocked, with Washington and Moscow unable to agree on a 150-kiloton testing limit, despite scientific opinion in both the East and West that underground explosions can be detected down to five kilotons or less.

Moscow is now prepared to permit on-site inspections - the U.S. demand that prevented agreement before - but Washington now says some testing has to continue to make sure stockpiled bombs still work.