North American junior middleweight champion Tony Chiaverini signed today to fight Sugar Ray Leonard in a 10-round nationally televised bout June 24 in Las Vegas.

The boxers originally were scheduled to meet in a nationally televised fight May 20 in Baton Rouge, La., but negotiations collapsed when promoters could not reach a financial agreement with Chiaverini. Leonard fought middleweight Marcos Geraldo instead and won a unanimous 10-round decision. Leonard, of Palmer Mark, Md., is unbeaten in 21 pro fights.

Chiaverini had hoped to land a world title fight this summer against either WBC middleweight champion Maurice Hope or WBA champion Hugo Corro. But the Hope camp has indicated its champion will remain idle until at least the fall and Corro has contracted to fight Vito Antuofermo June 30.

Chiaverini and Leonard have contracted to fight at 154 pounds.

Chiaverini, 26, has a 29-3-1 record, 20 knockouts. He is ranked fourth in the world among junior middlweights by the WBC and captured the North American title March 16 with a 10th-round knockout of Edgar (Mad Dog) Ross.

Chiaverini, ranked seventh in the world among middleweights by the WBA, has lost only once in the last 2 1/2 years and has a string of eight straight wins.