Battles between forces loyal to Tajik General Atta Muhammad and his rival Uzbek General Abd al-Rashid Dostum began on Wednesday and have claimed at least 70 lives so far.
Heavy artillery is being used by both sides just west of Mazar-e-Sharif.
Tanks have also been deployed, according to Afghanistan's interior minister, Ali Ahmad Jalali, who is in the city to help defuse the situation.
Aljazeera’s correspondent said the sheer intensity of fighting had sent aid workers fleeing from violence that threatened to engulf Mazar-e-Sharif itself.
Afghan political analyst, Sayyid Hishmat Allah Muslih, told Aljazeera.net it “was only a matter of time” before these old rivals began fighting each other again.
“General Muhammad’s deputy Abd al-Sabur says he has already lost more than 70 of his soldiers but General Dostum’s Sayyid Nur Allah was unwilling to number his casualties – but it is highly likely to be about the same,” Muslih added.
Nearing the city
Fighting on Thursday moved to within 20km of Mazar-e-Sharif, with the most violent clashes on the outskirts of Balkh.
Skirmishes initially erupted at Fayzabad, 60km to the west of the city and near to General Dostum’s stronghold of Sheberghan.
Muhammad heads the mainly Tajik Jamiat faction and Dostum - who is also deputy defence minister - heads the mainly Uzbek Junbish group.
General Muhammad wears a suit
nowadays, but still has an army
Tensions between the rival militias have been mounting since the weekend when two of Dostum's commanders were allegedly kidnapped by Muhammad's forces in Kod-e-barq.
Both generals command corps that are nominally under the control of the ministry of defence.
Pakistan border problem
Tension on Afghanistan’s southern border with Pakistan also shows no sign of easing.
Pakistani special forces arrested another 10 tribesmen for refusing to hand over three people who allegedly harboured Taliban and al-Qaida fighters, bringing the total arrested in a two-day sweep to 42.
Speaking from Wana in south Waziristan, administrator Anwar Ali Shah confirmed the arrests and the financial pressure now placed on the Zalikhel and Karikhel tribes.
Authorities also suspended special monthly allowances for the tribesmen.
The three wanted men are believed to have sheltered the wanted men in their residential mud-walled compounds near Angoor Ada, 5km from the Afghan border.
Last week, eight Afghans and two Pakistani soldiers were killed while arresting 18 Taliban and al-Qaida suspects.
The men arrested were Uzbeks, Afghans and Pakistani nationals, an intelligence official in northwest frontier city Peshawar said on Saturday.
Local residents deny any of them were al-Qaida or Taliban members, and have accused the government of executing last week's operation to appease the United States.
"The [Pakistan] government in a bid to appease the US is conducting this operation in the name of al-Qaida," tribesman Ahmad Sakhi told journalists.