Bulgaria has expressed grave concern at the growing tensions that have led to deaths, injuries and damage in southern Israel and Gaza and has urged the parties involved to end the violence immediately.

"We believe that the only certain path to a lasting solution to the longstanding problems between Palestinians and Israelis is the path of dialogue and negotiations," Foreign Ministry spokesperson Vessela Tcherneva said on March 13 2012.

On March 12, Israeli airstrikes killed six Palestinians in the Gaza Strip and Palestinian militants fired more rockets into southern Israel, in a fourth day of fighting that drew renewed concern from the international community, the Voice of America reported.

Palestinian medics said that the March 12 airstrikes on Gaza killed four militants and two civilians - a man in his 60s and his daughter. The Israeli military said its aircraft hit several militant targets, including a weapons storage facility and rocket launching sites. 

Gaza militants fired at least 30 rockets at southern Israel during the day, with several landing inside Israeli communities. No casualties were reported. 

Israeli airstrikes in Gaza had by March 12 killed 24 Palestinians, all but four of them militants, since the fighting erupted on Friday. The militants have fired more than 100 rockets at southern Israel, wounding several Thai agricultural workers, forcing schools to close, and disrupting the lives of hundreds of thousands of Israelis.

On March 13, Israel said that Palestinian militants had fired at least five rockets toward southern Israel since an Egyptian-brokered cease-fire took effect on Tuesday, VOA said.

Officials say no injuries have been reported from the rockets, which landed in open areas.

Earlier, Egypt said it had negotiated a truce between Israel and the Palestinian militants in the Gaza Strip.

The same day, the BBC reported that the United States had condemned the rocket attacks as "cowardly"; the Arab League called the Israeli air strikes "a massacre".

United Nations Secretary General Ban Ki-moon expressed grave concern over the flare-up in violence, describing rocket attacks on Israeli civilians as "unacceptable" and urging Israel to "exercise maximum restraint".

Discussing the newly implemented ceasefire between Israel and armed Palestinian factions in Gaza, Israeli internal security minister Yitzhak Aharonovich said, as quoted by Israeli news website Ynetnews: "There is an understanding that they stop firing and we stop firing. The minute they stop we have no interest to continue. But if another targeted assassination like last Friday’s is necessary, we will carry it out and enter another round, if need be."
 
"This round (of violence) was too long, unnecessarily so. A million residents (in the south) lived in uncertainty, and we should have intensified our response. We need to learn our lessons so that next time the response will be harder and more painful," he said during a visit to South District Police headquarters in Beersheba.