The alert sounded moments after Israel announced it is prohibiting Israelis from crossing the Taba border point into Egypt following an alert against an attack targeting Israelis.
FILE - In this October 28, 2011 file photo, a girl walks on a pier at the Red Sea beach town of Taba, in Egypt's Sinai Peninsula.
In the wake of two deadly Church bombings in Egypt on Sunday, the Israeli government told all its citizens travelling in the Sinai Peninsula to leave immediately and return to Israel. It appears that the attack was related to previous exchanges of fire in the area between the Egyptian Army and terrorists. Under the closure, Israelis citizens will not be allowed to cross into the Sinai, but will be allowed to return to Israel through the crossing point.
"Israel sends condolences to the families of those murdered in the attack in Egypt and wishes for recovery for the injured", the Prime Minister's Office said in a statement.
"Those bombers who target churches are marginal members of the terrorist group who have been newly recruited to be easily convinced to kill Christians", he continued, stressing that fresh militant recruits could easily be mislead to kill innocent civilians of other religions. Authorities added that there is increased "motivation to carry out terror attacks in different arenas at this time" due to ISIS's territorial losses in Iraq and Syria.
Assad: Washington's Attack Fails to 'Raise the Morale of US-Backed Terrorists'
It condemned the chemical attack, without naming Assad, calling instead for an global investigation to identify the perpetrator. New strikes hit outside the town on Sunday, with no immediate reports of casualties, the monitor added.
The weeklong festival is widely celebrated in Israel even among otherwise nonreligious Jews. It is expected to reopen next Tuesday, April 18, with the end of the Passover holiday, but that decision will only be made following a security assessment, the ministry said in a statement.
The Israeli government statement says intelligence information shows "increased activity by Islamic State" militants in Sinai.
Israel's anti-terrorism office issued the recommendation on Sunday, citing what it said was a heightened alert level and twin church attacks. However, no organisation took immediate responsibility for the attack.
Earlier on Monday morning, in an unusual move, the Taba border crossing between Israel and Sinai was closed.