JERUSALEM, Nov. 18 (Xinhuanet) -- An Israeli tank mistakenly killed three Egyptian security officers near the border early Thursday, an incident that Israeli Deputy Defense Minister Ze'ev Boim termed as "regrettable and grave in its outcome."

   The Israeli tank crew, operating near the Philadephi Route in the Rafah area bordering the Palestinian lands and Egypt, apparently thought the three to be Palestinians smuggling weapons.

   The tank then fired a shell across the border before dawn and killed the three, a senior Israeli security source told the Israeli newspaper Ha'aretz.

   "Three Egyptian troops were killed," the source said. "Our tank thought they were Palestinian weapons smugglers."

   The Israeli Foreign Ministry will join senior defense officials in an immediate investigation into the incident.

   The investigation is to examine a number of possible scenarios, including the possibility that the tank crew was firing at another target but missed, hitting the Egyptian soldiers instead.

   Boim said that the area was very sensitive, with Israeli troops always on high alert for terrorist activities.

   He said that the Egyptian army had also increased its operations in the area to prevent arms smuggle into the adjacent Gaza Strip.

   The Israeli army issued a formal apology to the Egyptian army, and scheduled a two-hour break in all training later in the day to discuss ways to prevent similar incidents.  Enditem