ISLAMABAD, Pakistan (CNN) -- Hundreds of militants, believed to be foreign fighters, launched attacks on various military check posts in Pakistan's border with Afghanistan Saturday night and early Sunday morning, military officials said.
A Pakistan soldier on patrol last fall against militants on the border of the Mohmand agency district.
The ensuing fighting left 40 militants and six Pakistan soldiers dead, said military spokesman Gen. Athar Abbas.
"This is one of the largest attacks we have seen," Abbas said.
The attacks occurred at checkposts and military camps in the Mohmand agency, part of the lawless Federally Administered Tribal Areas where U.S. and Pakistani officials have reported a presence of militants.
Abbas said the fighters crossed into Pakistan from Afghanistan, and used rocket launchers and machine guns in their attacks. They have since been repelled, he said.
Pakistan and Afghanistan share a porous 1,500-mile border.
In recent months, Afghan officials have blamed militants operating from havens in the lawless tribal regions of Pakistan of sneaking into their country and attacking security personnel.
Pakistan has repeatedly denied involvement and bristled at the accusation, saying that Afghan lawmakers were making allegations without proof.
Abbas' Sunday comments reverse those allegations, with Pakistan now blaming militants from Afghanistan attacking inside its soil.