President Reagan Friday paused on the campaign trail to approve legislation providing for U.S. participation in an anti-genocide treaty signed by Harry Truman in 1948 but long blocked by conservatives.

"I am delighted to fulfill the promise made by Harry Truman to all the peoples of the world - and especially the Jewish people," Reagan said in a statement released at the White House in advance of his action.Reagan recalled the Nazi death camps that claimed millions of Jews, Slavs, Gypsies and others in World War II and noted that similar horrors have occurred in Cambodia, the Ukraine and Ethiopia.

These events "only renew our rage and righteous fury and make this moment all the more significant for me and all Americans," Reagan said.

The president signed the bill at O'Hare International Airport outside Chicago while on his way to a rally for Vice President Bush and his running mate, Dan Quayle.

The genocide treaty was ratified by the Senate in 1986, handing a personal triumph to Sen. William Proxmire, D-Wis., who made more than 3,000 Senate speeches over 19 years urging ratification. Proxmire is retiring from the Senate this year.

After the ratification, implementing legislation was still needed to give the treaty the force of American law. It is this legislation, passed by the Senate Oct. 14, that Reagan agreed to sign.