The Chinese official news agency quoted TOLO television as saying Omar was killed en route from Quetta to North Waziristan in Pakistan. Similar reports were carried by other local TV channels, including Shamshad, Ariana and Noor but none gave any details.
Xinhua quoted an Afghan security official as saying, "It is correct that Mullah has been killed" in Pakistan.
But Xinhua said a Pakistan Urdu-language television channel reported a spokesman for the Pakistan Taliban had said reports of Omar's death were untrue.
CNN-IBN in India quoted Hamid Gul, former head of Pakistan's Inter-Services Intelligence Directorate, as saying there was no reason for Omar to be in Pakistan.
Omar has been in hiding since the Taliban regime in Afghanistan fell in 2001. There has been an escalation of violence in that country lately with the start of the Taliban summer offensive, which comes ahead of the likely start of the withdrawal of U.S. troops in July.
Pakistan-U.S. relations have been strained since a U.S. Navy SEAL team killed al-Qaida leader Osama bin Laden in a May 2 raid on his compound in the Pakistan garrison town of Abbottabad, northeast of Islamabad.