Washington, Dec 3 (IANS): In a continuing standoff over the NATO strike along the Afghanistan border that killed 24 Pakistani soldiers, Islamabad has refused to participate in the US investigation of the incident, according to the US Defence Department.

The US has asked Pakistan to be part of the investigation, but the Pakistanis have "elected to date" to not participate, department spokesman George Little said Friday referring to the bombing as a "bump in the road" for US-Pakistani counterterrorism co-operation.

As the US-Pakistan relationship hit an all-time low over the incident, US and Pakistani officials both said there was communication between the two sides before the controversial airstrike last weekend, but they differed on the content of those conversations.

US officials said Pakistani troops had "given the go-ahead" for the strikes, The Wall Street Journal reported Friday. CNN also cited two unnamed US officials as saying US troops did not tell Pakistani authorities about the mission ahead of time, because they thought it would take place entirely within Afghanistan.

CBS cited Pakistani military officials as saying US officials gave Pakistan soldiers the wrong location when asking for clearance to attack militants along the border.