Pakistani President Pervez Musharraf has criticised Afghanistan for not doing enough to fight Taleban militants operating on their shared border.
Gen Musharraf says the problem lies in Afghanistan
Gen Musharraf told reporters at the UN in New York that it was up to Kabul to take action against the militants.
The two countries share a 1,400-mile (2,250km) mountainous border which is extremely difficult to patrol.
Taleban and al-Qaeda elements are believed to be operating on both sides of the border.
Earlier on Wednesday, Afghan President Hamid Karzai called for the destruction of what he said were terrorist sanctuaries in the region.
Mr Karzai did not mention any country by name - but in the past he has accused Pakistan of harbouring Taleban militants, a charge that Pakistan denies.
"The problem lies in Afghanistan, and that is creating the problem in Pakistan," Gen Musharraf was quoted by the Associated Press news agency as telling reporters on the sidelines of the UN General Assembly meeting.
"I'm already doing a lot in Pakistan. They need to be doing more in Afghanistan."
"Instead of this blame game that goes on, [President Karzai] must realise what is the correct environment and take action accordingly in Afghanistan," Gen Musharraf said.
The two leaders are to due to meet President Bush in Washington next week.
In the past, both countries have accused each other of doing too little in the fight against the militants.
In May, Pakistan rejected accusations by Mr Karzai that it was encouraging Taleban militancy.
In March, Gen Musharraf said that Mr Karzai had given him "old and outdated" information about the Taleban.
He said Mr Karzai had informed him that the fugitive Taleban leader Mullah Mohammed Omar was hiding in Pakistan.
Mr Karzai had rejected the criticisms, saying that intelligence given to Pakistan was up-to-date.
Kabul wants Islamabad to crack down on Taleban rebels who launch attacks in Afghanistan. Pakistan denies claims it is lax on militants in border areas.
The Taleban have been blamed for an increase in violence in recent months, including a spate of suicide bombings inside Afghanistan.