Israeli fighter jets struck Gaza overnight in response to incendiary balloons launched over the frontier into Israel, the military said early on Friday.

       There were no immediate reports of casualties from the strike, which the Israeli military said targeted a facility used by Hamas fighters to research and develop weapons.

       It was the third time Israel has carried out airstrikes in Gaza since the end of the 11-day period of attacks and bombings on the territory and its Hamas rulers in May. Each came after activists mobilised by Hamas launched incendiary balloons that caused fires in nearby Israeli farming communities.

       Hamas uses such tactics to pressure Israel and international mediators to ease a crippling blockade imposed on Gaza when it seized power from rival Palestinian forces in 2007. Israel has vowed to respond to even minor attacks.

       Egyptian and international mediators have been trying to shore up the informal ceasefire that ended the most recent period of violence. In recent days, Israel has eased restrictions to allow in Qatar-funded fuel, extend Gaza’s fishing zone and permit increased cross-border commerce.

       Israel says such steps are contingent on Hamas preserving calm along the frontier.