Afghan Colonel Qudrat Allah told the Pakistan-based Afghan Islamic Press (AIP) he saw around 40 bodies on the battlefield in the Tangi Chinaran area of Dai Chopan district on Thursday.
Afghan officials had already claimed 70 Taliban dead in the first three days of fighting, as US special forces continue to search for an estimated 1000 fighters.
But the US military has confirmed only 14 killed in clashes so far.
While estimates vary, recent reports of regrouping Taliban are raising concerns that the movement has rallied support to undermine the US-backed central government.
Zabul governor Hafiz Allah said at least four Taliban had been killed by around midday on Thursday, before the heaviest clashes began.
But "the bombing is also still going on," he said, adding that he knew of injuries to three of his Afghan soldiers.
There are about 10,000 US troops in Afghanistan, making up the bulk of a 12,500-strong force hunting for remnants of the Taliban and al-Qaida organisations.
Asked about reports that the Taliban's supreme leader Mulla Muhammad Umar may be among the fighters, he replied:
Usama bin Ladin and Mulla Umar
yet to be killed or captured
"I cannot tell you about that. I am not sure. I have not seen him with my own eyes."
An Afghan military commander was reported as saying on Wednesday that Mulla Umar may be hiding with 800 Taliban fighters in mountains pounded by US war planes.
General Garni, military commander of the southeastern border province of Zabul, made the claim in an interview with AIP.
Fourth day of campaign
Aircraft have been raiding bases in Zabul's Daichopan district since Monday – a region 300km southwest of Kabul.
The mountains lie 180km from the border with Pakistan, where many Taliban are believed to be regrouping to stage a campaign against soldiers and officials in Afghanistan.
Garni said the fighters hiding with Mulla Umar included Afghans, Pakistanis and Arabs.
The 20-month US-led hunt for Taliban and al-Qaida members in Afghanistan has so far failed to come close to netting either Mulla Umar or al-Qaida’s Usama bin Ladin.
Umar deserted his headquarters in the southern city Kandahar in December 2001 as the Taliban surrendered their last stronghold to US-led forces.