ISLAMABAD, Pakistan — A major Uzbek militant group closely allied with Al Qaeda announced Saturday that its leader had been killed in an American drone strike in Pakistan’s tribal belt, along the Afghan border.

In a message on its Web site, the group, the Islamic Movement of Uzbekistan, said that Uthman Adil, who was its leader for just a year, had died. A senior Pakistani security official confirmed Mr. Adil’s death.

The news will bolster the Obama administration’s claims that the drone program led by the C.I.A. is successfully degrading Al Qaeda and its allies in Pakistan, despite strenuous Pakistani objections and continuing controversy over civilian casualties.

The group’s Web site said that Mr. Adil was killed in April, around the time that an American drone fired missiles into a militant hide-out in Miram Shah, in the North Waziristan tribal region, killing four people. The group may have delayed the announcement of Mr. Adil’s death to first choose a new leader. SITE Intelligence, an organization that monitors jihadist Web sites, said Mr. Adil’s deputy, Uthman Ghazi, had succeeded Mr. Adil.