Afghan national Army (ANA) troops arrive near the site of an ongoing attack on an army headquarters in Afghanistan April 21, 2017.

As many 140 Afghan soldiers were killed on Friday by Taliban attackers apparently disguised in military uniforms in what would be the deadliest attack ever on an Afghan military base, officials said.

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 official casualty figures.

A US 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, talked their way onto the base and opened fire on soldiers eating dinner and leaving a mosque after Friday prayers, according to officials.

The attackers used rocket-propelled grenades and rifles, they said.

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.

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 Western-backed Afghan government is locked in a prolonged war with Taliban insurgents and other militant groups.

Afghan national Army (ANA) troops keep watch near the site of an ongoing attack on an army headquarters in Afghanistan April 21, 2017.