Col. Ilya Shabalkin said Maskhadov was killed during a "special operation," but he did not elaborate.
The Interfax news agency later quoted Shabalkin as saying Maskhadov had been killed in Tolstoy-Yurt, a village in the northern sector of Chechnya that generally has been under the tight control of Russian forces.
Interfax, citing Chechnya's Kremlin-backed deputy prime minister, Ramzan Kadyrov, also reported that Russian forces intended to take Maskhadov alive, but he was killed by careless weapons-handling by his bodyguards. Three of Maskhadov's closest associates were detained, Interfax reported.
Kadyrov also reportedly said he had planned that Maskhadov would surrender and be offered a high-ranking position in his own security force.
Television channel NTV showed footage of Federal Security Service head Nikolai Patrushev telling President Vladimir Putin that Maskhadov had been killed in Tolstoy-Yurt.
Putin responded, "There is a lot of work here. We must augment the effort aimed at the defense of the citizens of the republic."
The channel also showed footage of a shirtless bearded corpse that resembled Maskhadov.
Earlier Tuesday, Russian officials reported detaining three rebels who were planning a large terrorist attack on the administration building in Tolstoy-Yurt.
Maskhadov led the Chechen separatists who fought Russian forces to a standstill in a 1994-96 war and he became the republic's president after the Russian military withdrew.
But he appeared to lose substantial influence to Chechen warlord Shamil Basayev, and by the time Russian forces returned to Chechnya in 1999, he was believed to command loyalty among only a relatively small faction of fighters.
Last year, Russia's Federal Security Service offered a reward of up to $10 million for information that could help "neutralize" Maskhadov and Basayev.
Maskhadov was regarded by some observers as comparatively moderate, in contrast to Basayev, an adherent of the strict Wahhabi sect of Islam who has claimed responsibility for some of Russia's most horrifying terrorist attacks, including last year's seizure of a school in Beslan that ended with the deaths of more than 330 people, about half of them children.
Russian officials consistently have alleged Maskhadov was connected to terrorist attacks such as the school seizure and the 2002 seizure of 800 hostages at a Moscow theater. Maskhadov denied involvement in those attacks.
A temporary cease-fire called by Maskhadov expired late last month on the 61st anniversary of the Stalin-era deportation of Chechens to the barren steppes of then-Soviet Central Asia.
Maskhadov had ordered his fighters, including Basayev, to observe a weekslong cease-fire through Feb. 22, the eve of the anniversary. He also renewed a call for talks with the Russian leadership, which has consistently turned them down.
Russian officials had dismissed the cease-fire call as a publicity stunt and maintained that rebels kept up their attacks.