They have also pointed to apparent leadership problems within the Taliban since former leader Mullah Mohammad Akhtar Mansour was killed in a U.S. drone strike
The Afghan Taliban said on Tuesday they were launching new operations after the end of the holy month of Ramadan, dismissing reports that they had been weakened following a change of leadership in May.
Afghan government and NATO officials have said government forces have had growing success against the Taliban since U.S. commanders were granted more freedom to conduct air strikes and other operations against the insurgents.
They have also pointed to apparent leadership problems within the Taliban since former leader Mullah Mohammad Akhtar Mansour was killed in a U.S. drone strike and replaced by the hardline cleric Mullah Haibatullah Akhundzada.
The Taliban's chief spokesman, Zabihullah Mujahid, said reports of a reduction in insurgent operations during Ramadan reflected a natural slowdown during one of the hottest periods of the year when Muslims are required not to eat or drink during daylight hours.
"But the commanders of the American occupation forces and the puppet figures in Kabul got the wrong impression from this situation and think that Mujahideen have been weakened or are facing problems due to the change in leadership," he said.
With the end of Ramadan and the Eid holiday immediately afterwards, the insurgents, who are seeking to force the NATO-led coalition out of Afghanistan and bring in Islamic law, were moving on to the offensive and had seized three district centres in the past 24 hours.