JERUSALEM (Reuters) -- A rocket was fired into southern Israel on Saturday but exploded in an area of open desert causing no damage or injuries, a military spokeswoman said.

The spokeswoman declined to say from which direction the rocket might have been launched, although the Egyptian border on the west side has been more volatile recently.

"Last night an explosion was heard in the Arava area in southern Israel ... Following an examination in the area it was determined that the rocket was probably a Grad, and the incident is currently being reviewed," the spokeswoman said.

Palestinian militants in the Gaza Strip have fired Grad rockets at Israel from the coastal territory in the past, and Israel says militants have also crossed into the Sinai to carry out similar launches.

An Egyptian security source said a sweep of the Sinai border area was carried out and he was certain the rocket was not launched from Egyptian territory.

"The rocket wasn't launched by Palestinian elements or saboteurs in Sinai, as the area is fully secured on the Egyptian side. We have swept the border area ... but no evidence was found that the rocket was launched from Egyptian land."

Sinai governor Abdel Wahab Mabrouk also ruled out a launch from Sinai, saying: "This is illogical under the tightened security measures."

The open desert border between Israel and Egypt was relatively quiet for three decades after the two countries signed a peace treaty in 1979. But Israel says that since the fall of Hosni Mubarak, Cairo has lost its grip on the Sinai.

In April, Israel said a rocket fired from the Sinai hit the resort of Eilat, causing no injuries, while last August cross-border infiltrators shot dead eight Israelis. Israeli soldiers repelling the attack accidentally killed five Egyptian guards.