Israeli attack helicopters on Monday struck Hamas military positions in Gaza, officials said, after the country's army reported a balloon-borne "explosive device" from the Palestinian enclave targeted its territory.

Monday's raid, which resulted in damage to the Hamas positions but no casualties, was the third tit-for-tat exchange in as many days.

A Palestinian official said three military observation posts were hit in the south and centre of the Hamas-ruled coastal strip.

The Israeli military earlier said its air force struck "two Hamas military posts" in response to the latest launch of a balloon-borne device from Gaza.

"A cluster of balloons carrying an explosive device was launched from the southern Gaza Strip towards Israeli territory," an army statement said. "No injuries or damage were reported."

Palestinians in Gaza have for months flown clusters of balloons with incendiaries or explosives suspended beneath them across the border into Israel as weekly protests and clashes have flared along the frontier.

Air strikes hit Hamas positions over the weekend after Israel said balloons carrying explosives were launched on Saturday and again after it said explosive devices were hurled from Gaza on Sunday.

At least 251 Palestinians have been killed by Israeli fire since March 2018, the majority shot during the weekly border protests and others hit by tank fire or air strikes in response to violence from Gaza.

Two Israeli soldiers have been killed over the same period.

Israel and Hamas have fought three wars since 2008.