A US congressional panel has frozen $US700 million in aid to Pakistan until it gives assurances it is tackling the spread of homemade bombs in the region.
Representative Howard McKeon (Republican) told reporters that the United States wants assurances that Pakistan is countering improvised explosive devices in their country that are targeting coalition forces.
The freeze is part of a defence bill expected to be passed by Congress later this week.
The ABC reports the move reflects American frustration over what it sees as Pakistan's reluctance to fight insurgent groups. However, Islamabad says it is doing all it can.
The freeze affects only a fraction of the civil and military assistance given to Pakistan.
The United States has allocated $US20 billion in security and economic aid to Pakistan since 2001.