Pakistan's interior minister says Nato and Afghanistan are not doing enough to stop Taliban militants crossing the border from Afghanistan into Pakistan.
Rehman Malik told the BBC he blamed militants coming from Afghanistan for Friday's attack in Mohmand district.
The attack, the deadliest in Pakistan this year, killed more than 100 people.
Nato's Secretary General, Anders Fogh Rasmussen, said militants crossing the border was a "matter of concern" and a major problem in Afghanistan too.
"I don't have detailed information about this specific case but I will not rule out the possibility," he told the BBC, when asked how he responded to Mr Malik's criticism.
"It just stresses the need for strengthened co-operation between [the Nato-led force] Isaf, Pakistan and Afghanistan when it comes to control of the borders."
Friday's devastating bombing happened in an area the Pakistani government had recently claimed had been cleared of militants and said was safe for civilians to return to.
Mr Malik disputed the widely-held belief that Pakistani militants are freely heading in the other direction to fight coalition troops.
He said he had intelligence information to prove that the attackers had crossed the border from Afghanistan.
He said he had "demanded" that the Afghan government and Nato "stop border infiltration".
But the BBC's Aleem Maqbool in Islamabad says there is considerable evidence to suggest militants have been heading in the opposite direction relatively freely - something Mr Malik claims his government has put a stop to.
Our correspondent points out that the attacks in Pakistan have been taking place not just in tribal border areas like Mohmand, but right across the country.
That, he says, has caused a great deal of anger among Pakistanis, many of whom believe their government simply does not have the right strategies in place, or the competence, to reduce the threat.