"We have seen these reports in the media and the concerned authorities are verifying these claims by the militants," Foreign Office spokesman Aizaz Chaudhry said.
Militants affiliated with the banned Tehrik-e-Taliban Pakistan, an umbrella organisation of over a dozen rebel groups, have claimed that some 120 fighters have been sent to Syria so far.
"So far, 100 fighters have reached Syria and 20 more are on the way. More volunteers are eager and ready to go," a militant source told PTI.
Some independent observers have expressed doubts about these claims, saying the Taliban are trying to exaggerate their potential to carry out operations overseas.
A senior journalist working for a private TV channel in Peshawar told PTI that the land route from Pakistan to Syria passes through Iran, and it was hardly likely that Tehran would allow Sunni rebels to cross over to topple a Shia ruler.
The claim by the Pakistani militants coincides with reports of an influx of hundreds of fighters from across world into Syria to remove the ruling Shia al-Assad regime.