Afghanistan has rejected criticism from Pakistan that its intelligence on militants is out of date.
The fighting has caused widespread destruction in Miran Shah
A spokesman for President Hamid Karzai said information about the Taleban and al-Qaeda was "strong and accurate".
The two countries have stepped up a war of words in recent days as fierce clashes rage between Pakistani troops and suspected militants on the border.
About 140 militants have died in recent fighting in North Waziristan's capital, Miran Shah, Pakistan's army says.
The BBC's Haroon Rashid in Miran Shah says the town is deserted, with many buildings and vehicles damaged, and there is a heavy troop presence.
President Karzai's spokesman, Karim Rahimi, said Kabul would provide Islamabad with more assistance, and defended its intelligence to date.
"It still shows that there are problems and terrorists have freedom of movement in Pakistan," he told a news conference in Kabul.
Earlier, Pakistani Prime Minister Shaukat Aziz told the BBC that "many elements cross over from Afghanistan into our territory" and defended Pakistan's response, including military action.
"We believe that on both sides of the border action should be taken, but Pakistan is fighting such elements."
Foreign Ministry spokeswoman Tasnim Aslam said Pakistan wanted Afghanistan and US-led coalition forces to "equally contribute in stopping militants".
Thousands of people have been fleeing fighting at Miran Shah
Pakistan and Afghanistan have long both accused each other of not doing enough in the US-led "war on terror", in which they play key roles. Security was high on the agenda when President Bush visited the region last week.
Relations have deteriorated since President Karzai handed his counterpart, Pervez Musharraf, a list of militants last month, who Kabul says are hiding in Pakistan.
President Musharraf says the list is based on old information and an attempt to malign Pakistan.
"Two-thirds of it is months old," he told CNN in an interview broadcast on Monday.
Correspondents say these are the fiercest clashes between the Pakistani army and pro-Taleban militants since troops went into the area three years ago.
On Monday, 19 militants - including foreign militants - were killed when security forces moved in to Miran Shah to retake a telephone exchange building that had been occupied at the weekend, officials said.
Helicopter gunships were used to end sporadic but continued resistance around Miran Shah. A daytime curfew was imposed.
Abdul Qayyum, a senior security official for Pakistan's tribal areas, said about 140 "miscreants" had been killed by troops in Miran Shah, Mir Ali and elsewhere in the area since 2 March.
Several hundred militants seized government buildings in Miran Shah on Saturday. It followed the bombing of an alleged militant hideout by security forces last week that killed dozens of people.
The main bazaar in the town is without electricity, and the only telephones that are working are those used by the local administration, our correspondent says.
He was among three journalists working for foreign news organisations who were detained by military authorities on Monday.
Thousands of people have already fled Miran Shah, while many more continue to leave to escape the clashes, witnesses said.
"We were waiting for the day. It was fighting all night and we feared that we might be hit by fire from a helicopter," Mohammad Anwar, a resident who was fleeing with his family, told the Associated Press.
"Helicopter gunships have been pounding militant positions around Miran Shah... the situation is very tense," another resident told the Reuters news agency.