Israeli troops killed three Egyptian soldiers along the border between Egypt and the Gaza Strip. Israel has apologized for what it says was an "operational mistake" and has begun an investigation into the incident.

The incident occurred in the early morning hours, Thursday, along the Philadelphi Road -- a patrol corridor running along the Gaza border with Egypt. It is an area where Israeli soldiers often battle Palestinian militants they accuse of smuggling in weapons from Egypt.

The Israeli Army says its troops had spotted three Palestinian militants planting a bomb in the area and ordered one of its tanks to open fire. Instead, the tank mistakenly fired on the three Egyptian border policemen who were on patrol nearby. The army says it has launched a "thorough" investigation and issued an immediate apology.

The incident comes at a time when Israel is particularly eager for Egypt's cooperation in ensuring security in the Gaza Strip when Israel carries out its planned withdrawal from the Palestinian area, next year.