Afghanistan's government and the U.S.-led coalition supporting it do not have the wisdom to solve the nation's crisis.
The U.S. military said two coalition soldiers had been killed in combat that also left about 45 militants dead. Also, President Hamid Karzai called for more coordination between coalition and tribal leaders in counterterrorism operations.
U.S.-led forces are waging their largest anti-Taliban offensive to date across southern Afghanistan to quash the deadliest campaign of militant violence since the Islamists' ouster in 2001.
The recording aired by independent Pakistan station Geo TV was apparently made during a recent meeting of Taliban leaders in Helmand province, the network said. Its authenticity could not immediately be confirmed.
"They cannot solve the issue of Afghanistan based on their wisdom and thinking," the speaker said.
The station's reporter said the recording also included Omar's claim that the Taliban control large areas of the country.
Geo said the tape came in an e-mail from purported Taliban figures in the capital, Kabul.
The audio recording, if confirmed as Omar's, would be his first since July 2005, when he vowed that the Taliban would continue to fight coalition forces.
Karzai did not comment on the tape's authenticity during an interview with a cable news network. But he said that if Omar is "really in charge," he should emerge from hiding and "face the danger that he is causing to hundreds of young people in Afghanistan and Pakistan."
"It needs guts to do what he's talking about, and he doesn't have it," Karzai told CNN's "Late Edition."
Omar led the Taliban in the capture of Kabul in 1996. Following the Sept. 11 attacks in the United States, an American-led military campaign invaded Afghanistan and toppled the Taliban for harboring al-Qaida leader Osama bin Laden and his group.
Karzai said Omar and the Taliban do not represent a threat to Afghanistan's government.
"They exist in the form of attacking schools, attacking children, killing innocent people," he said. "They are no match for our power."
The two coalition soldiers died at a hospital after they were wounded during a four-hour gunbattle Saturday, the U.S.-led coalition said in a statement. Another coalition soldier also was wounded.
The identities of the slain soldiers were not released.
The coalition estimates about 250 insurgents have been killed since Operation Mountain Thrust got under way earlier this month to stop a wave of suicide attacks and ambushes.
At a meeting in Kabul, Karzai emphasized to key Western officials the need for international troops to work more closely with tribal leaders and community elders during military operations, his office said.
The president told Western diplomats and the heads of NATO and U.S. forces in Afghanistan that the international community should examine the root causes of terrorist activities.
He again warned that maximum caution was needed to avoid civilian casualties during military operations.
The meeting followed strong statements from Karzai last week that the current approach of hunting down Taliban militants has failed to address the funding, training and recruitment that fuel terrorism.
In eastern Afghanistan, a police official said five Afghan aid workers, including two doctors and an employee of a Swedish aid organization, had been kidnapped.
Two doctors, an employee of the aid agency Swedish Committee for Afghanistan and two local government workers were kidnapped Thursday while driving in Nuristan province, said Ghalamullah Nuristani, the provincial deputy police chief.
Abdallah Fahim, spokesman for the Public Health Ministry in Kabul, said the five hostages were still alive and that police and Afghan troops were looking for them.