Israeli warplanes struck four new Hamas positions in the southern Gaza Strip on Thursday, as a flare-up continued to threaten a 2014 ceasefire agreement.

"In response to the ongoing attacks against Israeli forces, IAF aircraft targeted four Hamas military posts in the southern Gaza Strip," an army statement said, referring to the blockaded Palestinian enclave.

There were no immediate reports of casualties during the raids, which Palestinian security sources said struck farmlands near the border.

The army said Hamas had "repeatedly fired and launched mortar rounds" across the border, saying there had been 10 such incidents since Wednesday.

Hamas has accused Israeli forces of encroaching into Gazan territory.

The bombing raids follow four similar attacks overnight Wednesday that injured four people, including three children, Palestinian and Israeli security officials said.

The uptick in violence, the first time the two sides have fired at each other directly since a 2014 war, has raised fears that a ceasefire agreement could fail.

Israeli general stirs controversy with Holocaust remark
Jerusalem (AFP) May 5, 2016 - An Israeli army chief has sparked controversy by appearing to compare contemporary Israeli society to Nazi Germany, in remarks delivered ahead of Thursday's Holocaust Remembrance Day.

Deputy chief of staff Major General Yair Golan said in a speech Wednesday marking the beginning of the commemorations that the Holocaust "must bring us to reflect deeply on the nature of man, even when that man is ourselves".

"If there is something that frightens me with the memory of the Holocaust, it is identifying horrifying processes that happened in Europe, and specifically in Germany, 70, 80 and 90 years ago, and finding testimony to them amongst us, today, in 2016," he said.

"There is, after all, nothing easier and simpler than hating the foreigner... arousing fears and terrifying," he said.

Education Minister Naftali Bennett of the nationalist rightwing Jewish Home said Golan had "made a mistake and should immediately correct" it before "Holocaust deniers make these erroneous words a banner and our soldiers are compared to Nazis".

Isaac Herzog, leader of the opposition Labour party, praised the "courageous" Golan.

"The crazies who will start screaming at him now should know -- that's what moral and responsibility sound like," he wrote on Twitter.

The military spokesperson's office on Thursday "clarified" that Golan "had no intention whatsoever to compare the IDF and the state of Israel to the horrors that occurred in Germany 70 years ago."

"This is an absurd and baseless comparison that he never would have made and it was never his intention to criticise the Israeli government," a statement read.

Golan's commander, chief-of-staff Lieutenant General Gadi Eisenkot, had angered politicians in February with remarks advocating proportionate responses to Palestinian assailants carrying out stabbing attacks on soldiers.

International Holocaust Remembrance Day is held on January 27 but Israel commemorates it separately on Thursday.