Afghan police say at least 22 people were killed in the northern province of Kunduz on August 8 when a Taliban suicide bomber drove a vehicle loaded with explosives into a group of pro-government militia and detonated it.
Kunduz police spokesman Sarwar Hussaini said the attack took place in the province's Khanabad district at a gathering of the militia, known as Arbakis, late on August 8.
He said most of those killed were thought to be pro-government militia who have been fighting an offensive launched earlier this year by the Taliban and Central Asian extremists who have sworn allegiance to the Islamic State militant group.
The attack comes a day after a wave of similar bomb attacks in Kabul killed at least 51 people -- including 15 civilians, 27 Afghan police recruits, eight civilian contractors at a military base near Kabul airport, and one NATO soldier.
The three separate attacks on August 7 marked the bloodiest day in Kabul since the withdrawal of most international combat troops at the end of 2014.
In Washington, the White House said national security adviser Susan Rice had spoken with Afghan President Ashraf Ghani by telephone to express U.S. condolences.
It was also the first major attack since confirmation of Taliban leader Mullah Mohammad Omar's death in late July.
Divisions have broken out within the Taliban leadership after the appointment of Mullah Akhtar Mansur, a relative moderate, as new leader.
Previously seen as open to direct peace talks with the Afghan government, Mullah Mansur has since pledged to press on with the insurgency.
Security experts are attributing the escalation of violence in the heart of the Afghan capital on August 7 as an attempt by Mullah Mansur to boost his image among Taliban factions that support Mullah Omar's son as the next Taliban leader, and to drive attention away from the internal rifts over his leadership.
Security analyst Abdul Hadi Khaled said: "The new wave of attacks is a tactic by the Taliban's new leadership to show they are capable, potent, and operational."
Khaled said: "The demise of Mullah Omar divided the movement and affected the morale of their ground fighters. Hitting Kabul with a wave of powerful attacks is a way of showcasing their strength."
Wave Of Attacks
The first attack occurred when a powerful truck bomb tore through the city center just after midnight on August 7, killing 15 civilians and wounding 240 others.
Less than 24 hours later, a suicide attacker dressed in police uniform blew himself up at the entrance of a police academy in Kabul -- killing 27 and injuring 28.
Police say the attacker was wearing a police academy student's uniform when he walked into a group of recruits outside of the academy and detonated his explosives-laden vest.
The Taliban claimed responsibility for the attack.
NATO also confirmed that eight civilian contractors and one of its service members were killed in an overnight battle at a base used by U.S. special forces in Kabul called Camp Integrity, near Kabul airport. The facility was attacked with a car bomb before the battle with insurgents broke out.
The military alliance also said two militants were killed in that battle.
Foreign troops were also deployed in a gunbattle near Afghanistan's Counternarcotics Ministry in Kabul.
An Afghan security source told RFE/RL the foreign troops sealed off the ministry and replaced Afghan security forces there because foreign advisers were thought to be inside the ministry building.
The battle erupted at the bombings nearby, and gunfire continued into the early hours of August 8.
Under a security agreement between Kabul and the United States, most U.S. troops in Afghanistan serve a primary role as advisers and trainers for Afghan forces.
But U.S.-led coalition forces have the authority to take over security operations in order to protect foreign advisers in the country.
There was no confirmation of the nationalities of the foreigners thought to be sheltering inside the Counternarcotics Ministry while the gunbattle raged outside late on August 7.
But the U.S. Drug Enforcement Administration (DEA) works together with Afghanistan's Counternarcotics Police and Interior Ministry to support investigations targeting major narcotics trafficking organizations that support Afghan militants.
With reporting by dpa