Israeli troops on Saturday killed at least three Hamas militants who were en route to carrying out an attack, throwing a shaky truce along the Gaza-Israel border further into question.
The Israeli military said troops shot and killed four armed men near the border, while Palestinian medics said they found three bodies in the area and that a fourth person was seriously wounded.
Hamas said the three dead were members of its military wing. Saturday's incident marked the second time in four days that Hamas breached the cease-fire reached in November.
Earlier this week, Hamas fired a barrage of rockets toward Israel, causing no injuries, after Israeli forces killed nine Palestinians in fighting.
"The truce cannot be for free. There is a possibility to consider a temporary truce, on the condition that is mutual. Otherwise there will be no free truce," Abu Obeida, a spokesman of the Hamas military wing, told a local Palestinian radio station.
Hamas has sent mixed messages about the truce in recent days. While the military wing said it considered the truce to have ended, citing Israeli violations, political leaders said the future of the cease-fire depended on Israeli actions.
The Israeli military said Palestinian militants have attempted to plant more than 50 bombs near the border since the cease-fire took effect.