Islamic Jihad threatened on Saturday to resume rocket attacks on Israel if it continues military operations in the occupied West Bank, while Gaza's ruling Hamas said it had arrested militants and would lock up any violating a truce with the Jewish state.
The threats came after a Palestinian teenager was killed in Hebron in the West Bank overnight as he threw petrol bombs at Israeli soldiers, the military said, putting further strain on the week-old ceasefire.
Mohammad al-Alami, 17, was shot in the face and body by Israeli soldiers who came under attack with stones and fire bombs during clashes in Beit Umar, near Hebron, in the south of the territory, Palestinian police said.
Islamist group Hamas, which has controlled the Gaza Strip since it routed forces loyal to Palestinian president Mahmud Abbas a year ago, said it had already arrested some militants for breaking the truce.
Egypt negotiated a truce between Hamas and the Jewish state, aiming to halt rocket attacks in return for Israel's lifting of its blockade of Gaza. The truce however did not cover the occupied West Bank where Israel says it must carry out military operations for its own security.
Islamic Jihad on Tuesday fired three rockets at Israel in what it said was revenge for the death of one of its commanders in a firefight with Israeli troops in the West Bank.
Israel responded by again shutting Gaza's border crossings. It has not however resumed the near-daily air strikes and ground incursions it carried out in the months leading up to the truce.
The Erez passenger crossing, used by diplomats, journalists, and Gazans requiring medical care in Israel or abroad, has remained open, as did Nahal Oz fuel crossing.
'People have already been arrested'
Further rockets and mortar rounds fired from Gaza slammed into Israel on Thursday and Friday without causing casualties, the Israeli army said, putting extra strain on the fragile ceasefire.
"Islamic Jihad reserves the right to respond to all Israeli violations," one of the group's Gaza chiefs Khaled al-Batch said on Saturday, but added they would "not take the initiative in breaking the calm."
"If the crossing points (with Gaza) do not reopen, if the siege and the aggression does not stop, the calm will go up in smoke," Batch added, repeating that Israeli attacks in the West Bank would spark retaliation from Gaza.
"In the West Bank or in Gaza, we are the children of a single cause and a single land," he added.
Meanwhile one of Hamas' top chiefs, Mahmoud al-Zahar said the group would lock up anyone breaching the ceasefire and said several members of armed groups had already been arrested.
"There is an agreement between Islamic Jihad and Hamas stating that all people from Jihad or Hamas, who violate this accord will be arrested and their weapons confiscated," al-Zahar was quoted as saying in the Palestinian daily Al-Quds.
"People have already been arrested. Some opened fire on lorries and others fired rockets at the Nahal Oz (oil facility)," al-Zahar added.
He said that Hamas had even negotiated for some families to hand over their children to Hamas police for breaking the truce.
The agreement is supposed to halt all Palestinian attacks and Israeli military operations in and around the besieged Gaza Strip and eventually lead to the easing of the blockade on the densely populated territory.
Since Hamas seized power in June last year, Israel has sealed Gaza off to all but limited humanitarian aid, spawning widespread fuel shortages and crippling the local economy in the impoverished territory of 1.5 million people.