ISLAMABAD - Afghanistan’s largest television station has reported last Friday’s deadliest-ever assault by the Taliban on a major military base in northern Balkh province left more than 250 soldiers dead and accused authorities of “hiding the truth.”

The government has been under fire for refusing to reveal the number of casualties several days after the attack targeting the Afghan National Army’s 209th Shaheen Corps in the provincial capital of Mazar-i-Sharif.

The deputy chairman of the Afghan Senate, the upper house of the parliament, informed lawmakers on Sunday that security officials told him the death toll stood at around 131, while provincial politicians had put it at more than 150 from the outset.

“Based on information gathered from different sources, so far, the identity of 256 soldiers from 10 provinces have been confirmed,” TOLOnews reported Tuesday, quoting “credible” sources.

Coffins containing the bodies of Afghan national A Coffins containing the bodies of Afghan national Army (ANA) soldiers killed in April 21's attack on an army headquarters are lined up in Mazar-i-Sharif, northern Afghanistan, April 22, 2017. Coffins containing the bodies of Afghan national Army (ANA) soldiers killed in April 21's attack on an army headquarters are lined up in Mazar-i-Sharif, northern Afghanistan, April 22, 2017.

The TV station also named the provinces to which the bodies of the victims have been dispatched for burials.

Possible impact on morale cited

Government officials privately have insisted that releasing the death toll could undermine the morale of the Afghan army battling a resurgent Taliban. But critics assert the government was disrespecting the slain soldiers by withholding the number of casualties.

Officials and insurgents say a group of 10 heavily-armed Taliban fighters wearing army uniforms, and accompanying an allegedly wounded soldier, stormed the base and carried out the massacre. The attack mainly targeted a dining hall and mosque deep inside the facility where hundreds of Afghan soldiers were offering special Friday prayers.

Afghan soldiers stand guard at the gate of a milit Afghan soldiers stand guard at the gate of a military base in Mazar-i-Sharif, Afghanistan, April 21, 2017, after an attack by Taliban suicide bombers and gunmen who entered the compound wearing Afghan army uniforms. Afghan soldiers stand guard at the gate of a military base in Mazar-i-Sharif, Afghanistan, April 21, 2017, after an attack by Taliban suicide bombers and gunmen who entered the compound wearing Afghan army uniforms.

Witnesses and security sources said that Taliban assailants drove up to the base in two army vehicles mounted with machine guns, waving fake identification cards and claiming they were bringing back a seriously injured soldier from the frontline. Some of the attackers detonated explosives strapped to their bodies while others were gunned down by Afghan commandos before the hours-long siege ended.

Raid renews criticism

The brazen raid has renewed criticism of Afghan security institutions’ ability to stabilize the country. The carnage prompted the defense minister and the army chief to step down on Monday. President Ashraf Ghani has also removed several corps commanders, including that of the Shaheen Corps, following the attack.

A high-level investigation is underway to determine how the attackers managed to enter the highly-fortified military facility in Mazar-i-Sharif and whether they had received “inside help.”

FILE - In Afghanistan, the Taliban released to the The Afghan Taliban released to the media this photo which it said shows the suicide bombers and gunmen who attacked the army base in Mazar-i-Sharif, April 21, 2017. The Afghan Taliban released to the media this photo which it said shows the suicide bombers and gunmen who attacked the army base in Mazar-i-Sharif, April 21, 2017.

At least four Afghan soldiers are suspected of having helped the attackers but they remain at large, according to officials.

American military advisors and trainers were also present at a different location inside the regional military headquarters.

The Taliban, while claiming responsibility for Friday’s attack, said more than 500 soldiers were killed or wounded. It went on to say the assault on the army base was a prelude to its coming “spring offensive” in Afghanistan.

U.S. Defense Secretary Jim Mattis, during his day-long visit to Kabul on Monday, also warned “2017's going to be another tough year for the valiant Afghan security forces and the international troops.”