Hamas said on Monday that its security forces in the Gaza Strip are on the alert after Egypt's army vowed to avenge the killing of 16 guards by gunmen near the Israeli border.
Egypt's MENA news agency has said the gunmen were "jihadists" who "infiltrated from Gaza through tunnels" into the adjacent Sinai but Hamas has dismissed the idea that militants from inside their territory were involved.
"The national security services are on a 100-percent state of alert to maintain common security between the Gaza Strip and Egypt," Jamal al-Jarrah, head of the Hamas security forces, wrote on the interior ministry website.
He accused Israel of encouraging speculation that Gaza Palestinians were involved in Sunday's attack.
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"The occupation is trying to spread its rumours and hold Gaza responsible for the attack, to cause tension in relations between the Palestinian and Egyptian peoples," said Jarrah. "We assert that we are working around the clock to maintain common security."
The Hamas government in Gaza was due to meet later on Monday to discuss the situation.
Palestinian president Mahmud Abbas, speaking from his headquarters in the West bank city of Ramallah, condemned the attack.
"President Abbas, the Palestinian people and the Palestinian leadership condemn with the strongest of words this crime that was committed by the hands of a terrorist group," his spokesman Nabil Abu Rdeineh said in a statement
"Despite its gravity, this crime will not undermine the depth of relations between the two peoples and the Palestinian and Egyptian leaderships," he added. "It will not affect Egypt's national role in permanently committing to support our cause and our people's struggle."