ISLAMABAD  - Pakistan and the US on Friday agreed to keep on working collectively to curb use of homemade bombs, officials said.The US has frozen $700 million in aid to Pakistan until it gives assurances it is helping fight the spread of Improvised Explosive Devices (IEDs) in the region.The US officials urge Pakistan to curb the manufacturing of IEDs and also its exports to Afghanistan. They said that IEDs are used against the foreign forces in Afghanistan.A US delegation led by Dr Peter Lavoy, US Assistant Secretary for Asia and Pacific Security, met Pakistan Interior Minister Rehman Malik and discussed ways to counter the threat of IEDs. ‘The US official appreciated steps taken by Pakistan in countering IEDs’, an Interior Ministry statement said.  Militants in Pakistan also now use IEDs to target the security forces and pro-government tribal elders and political leaders in the country’s tribal regions and volatile northwest.Americans also say that IEDs are Taliban most effective weapons against US and coalition troops in Afghanistan.They say that many are made using ammonium nitrate, a common fertiliser smuggled across the border from Pakistan. Afghan officials in eastern Kunar province claimed this week that they seized a truck, carrying nearly eight tonnes of explosives used for making IEDs. They alleged that the chemicals were loaded in the truck in the Pakistani eastern city of Multan in the Punjab province.US officials insist that want assurances that Pakistan is countering IEDs in their country that are targeting coalition forces.The US official also discussed security cooperation with Pakistani Interior Minister, the official statement said.The Interior Minister asserted that the government is waiting for outcome of Parliamentary debate for new terms of engagement with the US, it said.