WASHINGTON (AP) - President Clinton urged the Senate today to act on a long-stalled treaty to ban nuclear testing, saying the United States' failure to act jeopardizes an agreement signed by 152 nations.

He said it would be "a grave error" for the treaty to be derailed because of a dispute with some senators over two unrelated treaties. "Unfortunately, the test-ban treaty is now imperiled by the refusal of some senators even to consider it," the president said.

Clinton, in an appearance in the Rose Garden, spoke up as part of a new drive by Democrats and Republicans alike to dislodge the Comprehensive Test Ban Treaty from the Senate Foreign Relations Committee. Clinton signed the treaty in 1996. Now the treaty has been signed by 152 countries, and 41 of them have ratified it.

"At a minimum," Clinton said, "the Senate Foreign Relations Committee should hold hearings this fall. Hearings would allow each side to make its case for and against the treaty, and allow the Senate to decide this matter on the merits.

"We have a chance right now to end nuclear testing forever," the president said. "It would be a tragedy for our security and for our children's future to let this opportunity slip away."

Under the treaty, all 44 states with some nuclear capacity must sign for it to take effect. Even one holdout could doom the treaty. So far, only 18 nations with nuclear capabilities have acted.

The treaty is bottled up in the Foreign Relations Committee by its chairman, Sen. Jesse Helms, R-N.C.

Before moving on the test-ban treaty, Helms wants the administration to first submit to the Senate modifications in the Anti-Ballistic Missile Treaty agreed to three years ago by Clinton and Yeltsin. The administration says it will submit the modifications, but only after Russia ratifies START II.

Helms also wants the administration to submit the climate treaty negotiated in Kyoto, Japan, in December 1997, even though it would likely be defeated.

Clinton said the ABM and climate treaties "are literally not ripe for presentation to the Senate yet" and it would be a "grave error" to delay the test-ban treaty.

Supporters of the test-ban treaty say it would lock in U.S. superiority gained by more than 1,000 nuclear tests during the Cold War. Failing to ratify the pact could open the door to additional nuclear tests by India, Pakistan or other nations, the supporters claim.

Opponents argue it could threaten America's ability to deliver an effective nuclear strike, if one is ever needed.