The Defense Ministry said the toll was "over 100" Afghan soldiers killed and wounded.
One official in the northern city of Mazar-i-Sharif, where the attack occurred, said on Saturday at least 140 soldiers were killed and many others wounded. Other officials said the toll was likely to be even higher.
The officials spoke on the condition of anonymity because the government has yet to release exact casualty figures.
The attack starkly highlighted the struggle by the Afghan government and its international backers to defeat a potent Taliban insurgency that has gripped Afghanistan for more than a decade.
A U.S. official in Washington on Friday had put the toll at more than 50 killed and wounded.
As many as 10 Taliban fighters, dressed in Afghan army uniforms and driving military vehicles, made their way onto the base and opened fire on mostly unarmed soldiers eating a meal and leaving a mosque after Friday prayers, according to officials.
The attackers used rocket-propelled grenades and rifles, and several detonated suicide vests packed with explosive, they said.
Witnesses described a scene of confusion as soldiers were uncertain who the attackers were.
The base is the headquarters for the Afghan National Army's 209th Corps, responsible for much of northern Afghanistan, including Kunduz province where there has been heavy fighting.
Taliban spokesman Zabihullah Mujahid said in a statement on Saturday the attack was retribution for the recent killing of several senior Taliban leaders in northern Afghanistan.
Four of the attackers were Taliban sympathisers who had infiltrated the army and served for some time, Mujahid said.
That claim has not been confirmed by the Afghan army.
The NATO-led military coalition deploys advisers to the base where the attack occurred to train and assist the Afghan forces but coalition officials said no international troops were involved in the attack.
"The attack on the 209th Corps today shows the barbaric nature of the Taliban," the commander of coalition forces, U.S. General John Nicholson, said in a statement on Friday.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)