The truce was only the fourth agreed pause in fighting in the two-decades-long conflict
Fighting between the Taliban and Afghan government forces resumed Sunday in the restive southern province of Helmand, officials said, ending a three-day ceasefire agreed by the warring sides to mark the Eid-ul-Fitr holiday.
There were clashes on the outskirts of Lashkar Gah, the capital of Helmand, which has seen intense fighting since the United States began its final troop withdrawal from Afghanistan earlier this month, an Afghan military spokesman and a local official said.
"The fighting started early today and is still ongoing," Attaullah Afghan, head of the Helmand provincial council, told AFP.
He said Taliban fighters attacked security checkpoints on the outskirts of Lashkar Gah and other districts.
An Afghan army spokesman in the south confirmed fighting had resumed.
"They [Afghan forces] started the operation... do not put the blame on us," Taliban spokesman Zabihullah Mujahid told AFP.
The three-day truce initiated by the Taliban and swiftly agreed to by the Afghan government had largely held during the Eid holidays that ended on Saturday.
The calm was broken on Friday by a blast at a mosque on the outskirts of the Afghan capital, which killed 12 people including the imam leading Friday prayers.
The Taliban denied it was behind the attack which has been claimed by the Islamic State group, according to the SITE Intelligence Group, which monitors jihadist groups.
The truce was only the fourth agreed pause in fighting in the two-decades-long conflict.
Violence had previously surged in several provinces of Afghanistan -- including former insurgent bastions Helmand and Kandahar.
It comes after negotiators from the Afghan government and Taliban said they had met in Doha on Friday to discuss speeding up peace talks, which opened in September but have made little headway.
"Both sides agreed to continue the talks after (Eid)," the Taliban tweeted.
As violence has soared, including a wave of targeted killings on Afghanistan's educated class, international efforts had been made to jump start the talks -- including a one-day conference in Moscow in March.
Turkey was also scheduled to hold an Afghanistan conference in late April but it was postponed indefinitely because the Taliban -- angered by Washington's withdrawal delay -- declined to attend.
Washington has vowed to end America's longest war but missed the May 1 deadline to withdraw all of its troops, as agreed with the Taliban in return for security guarantees and a promise to launch talks with the Afghan government, who were cut out of the deal.
President Joe Biden pushed back the date to September 11 -- 20 years after the United States invaded Afghanistan and ousted the Taliban.
US and Afghan officials on Friday said Washington had pulled out completely from a major southern air base in the former Taliban stronghold of Kandahar, just a week after US airstrikes.