An Israeli soldier was killed by a bomb on the border with the Gaza Strip on Tuesday and troops then killed a Palestinian, in the worst clashes since the conflict in Gaza ended.
The Israeli military said a bomb was detonated against its forces on the Israeli side of the border fence near the Kissufim crossing, killing one soldier and wounding another three.
Israeli fire shortly afterwards in the same area killed a Palestinian who medics said was a 27-year-old farmer.
The incidents were the bloodiest since the 22-day Israeli offensive that killed 1,300 people in the enclave ended in ceasefire declarations.
Neither the ruling Hamas Islamist movement nor its smaller allies claimed responsibility for the attack on the patrol.
However Hamas spokesman Sami Abu Zuhri praised the bomb attack on the troops as "a natural response to the crimes of the occupier". Two Palestinians were killed last week in incidents blamed on Israeli fire.
The violence took place as US President Barack Obama's new envoy, George Mitchell, arrived in the Middle East, seeking a more permanent truce.
He was due to hold talks on Wednesday with Israeli leaders.