* Flare-up has included heaviest rocket barrage in two years
* Egypt trying to mediate halt to violence (Adds Islamic Jihad announces ceasefire, Israeli air strike before truce)
By Maayan Lubell and Nidal al-Mughrabi
JERUSALEM/GAZA, March 13 (Reuters) - Egypt brokered a ceasefire on Thursday aimed at ending a flare-up of rocket attacks from Gaza on Israeli towns and Israeli air strikes in the Palestinian enclave, the Islamic Jihad militant group said.
There was no immediate word from Israel, but a senior Defence Ministry official said earlier in the day he expected the fighting to die down soon.
"Following intensive Egyptian contacts and efforts, the agreement for calm has been restored in accordance with understandings reached in 2012 in Cairo," Khaled al-Batsh, an Islamic Jihad leader, wrote on Facebook, referring to a truce that ended an eight-day Gaza war two years ago.
Batsh said Islamic Jihad, which began launching rockets into Israel on Wednesday after Israeli soldiers killed three of its fighters a day earlier, would hold its fire as long as Israel did the same.
Minutes before Batsh posted word of the truce on Facebook, Israeli aircraft struck targets in Rafah, in the southern Gaza Strip near the border with Egypt, wounding three Palestinians, witnesses said. The Israeli military said "seven terror sites" had been hit.
Hours earlier, sirens sounded in the southern Israeli towns of Ashkelon and Ashdod. Police said rockets had landed in open areas, causing no casualties.
On Wednesday, the Israeli military carried out 29 air strikes and fired tank shells at militant targets in Gaza after Islamic Jihad launched 60 rockets towards Israel in the heaviest such barrage in nearly two years.
No casualties were reported on either side of the frontier in Wednesday's incidents.
Prime Minister Benjamin Netanyahu said in a statement that Israel would "hit back with increasing force" against anyone who tried to ruin celebrations over the next few days of the Jewish holiday of Purim.
Palestinian sources noted that Gaza's ruling Hamas Islamist movement had not joined in the rocket attacks - a sign that it hoped to avoid widening the conflict.
But, the sources said, Hamas also had not moved immediately to try to stop the launchings, apparently concerned it would be seen by Palestinians as less committed than Islamic Jihad to confronting Israel.
Islamic Jihad has strong ties with Israel's arch-foe Iran and is the second largest faction in the enclave. [ID: nL5N0IF36D]
Last week Israeli forces seized a ship in the Red Sea which it said was carrying missiles to armed groups in Gaza. Officials said the arms may have been intended for Islamic Jihad. (Editing by Jeffrey Heller and Ralph Boulton)