At least 107 people-- including 87 Taliban, 15 police, an American civilian and a Canadian woman soldier -- were killed as the Taliban launched two suicide bombs and a major attack on Musa Kala village in Helmand province Thursday.
Speaking to tribal leaders and officials in Asadabad, in the eastern province of Kunar which borders Pakistan, Karzai said Pakistani intelligence gives military training to people and then sends them to Afghanistan with logistics.
But Pakistan should realize it no longer has the power to control events in Afghanistan, the Afghan Islamic Press news agency quoted Karzai as saying.
He also said Taliban leader Mullah Omar was a coward who was hiding in Pakistan and sending youngsters to kill Afghans.
Various madrassas, or Islamic schools in Pakistan were also urging students to go to Afghanistan to burn schools and clinics, he said.
The chief of staff for southern Afghanistan, British Colonel Chris Vernon, said the Taliban leadership was coordinating its campaign from the western Pakistani city of Quetta, near the Afghan border.
"The thinking piece of the Taliban is out of Quetta in Pakistan. It's the major headquarters," he told the Guardian. "They use it to run a series of networks in Afghanistan."
The Quetta leadership controlled "about 25" mid-level commanders dotted across the Afghan south, one of whom was captured last month, Colonel Vernon told the Guardian.
"Clearly the Taliban are at large in Balochistan, operating in Quetta. Obviously that's a cause for concern," the Guardian quoted a British diplomat in Islamabad as saying. "There's no evidence of a serious network of Taliban camps but it's easy for them to take cover in Afghan refugee camps."
Marijadeen Patan, the governor of Khost province in the southeast has also accused the Pakistani intelligence agency ISI of aiding and encouraging militants to attack international forces in Afghanistan.
These charges provoked strong protests from Pakistani officials.
"It is absolutely absurd that someone is talking like this. If the Taliban leadership was in Quetta we would be out of our minds not to arrest them. They should give us actionable intelligence so that we can take action," said military spokesman Major General Shaukat Sultan.