BAGHDAD, Iraq - Iraqi militants released three Turkish hostages today, shortly after another group of kidnappers claimed to have executed an American soldier captured nearly three months ago.

The killing of Spc. Keith Maupin, 20, of Batavia, Ohio, was reported by Arab television, which aired a videotape showing a blindfolded man identified by his captors as Maupin sitting on the ground. Al-Jazeera said that in the next scene, gunmen shoot the man in the back of the head, in front of a hole dug in the ground. The station did not broadcast the killing.

The U.S. military said it could not immediately confirm whether the man shown in the murky videotape was indeed Maupin. Maj. Willie Harris, spokesman for the Army's 88th Regional Readiness Command, said the videotape is being analyzed by the Defense Department.

Meanwhile, the father of a U.S. Marine who was reported kidnapped by militants on Monday issued a plea for his release. The captors of Cpl. Wassef Ali Hassoun have threatened to behead him.

The militants said they killed Maupin because the United States did not change its policies in Iraq and to avenge "martyrs" in Iraq, Saudi Arabia and Algeria.

Maupin was among nine Americans, seven of them contractors, who disappeared after an ambush on a convoy west of Baghdad on April 9.

Hassoun, an American Marine of Lebanese descent, was shown blindfolded, with a sword brandished over his head in a videotape aired on Al-Jazeera on Sunday. The militants threatened to behead him unless all Iraqis "in occupation jails" are freed. They did not set a timeframe.

"I appeal to the kidnappers and to their conscience and faith to release my son," his father, Ali Hassoun, said in an interview with The Associated Press at his house in the northern Lebanese port city of Tripoli.