Israeli warplanes bombed two separate targets in the Gaza Strip today after Palestinian militants fired projectiles across the border, the army said.
The strikes in northern Gaza came just hours after witnesses reported an Israeli army incursion across the Strip's eastern borders, to which Islamist militants claimed to have responded with mortar fire.
The military said "aircraft targeted two concealed rocket launchers in the northern Gaza Strip" in response to two projectiles that had hit Israel since yesterday.
An spokeswoman told AFP one of the projectiles was a rocket and the other a mortar round.
"Launching rockets against Israel and its civilians is a breach of our sovereignty. We maintain the right to operate against those who are involved in terror," said army spokesman Lieutenant Colonel Peter Lerner.
No casualties were reported in any of the attacks from either side.
Witnesses said earlier that Israeli troops backed by armour entered Gaza east of the southern town of Khan Yunis.
"Six military bulldozers accompanied by several tanks entered about 200 metres from the border into farmland, as helicopters and spy planes circled above near the village of Khuzaa," one witness told AFP.
"Resistance fighters fired several mortar rounds at the Israeli forces and explosions were heard in the area."
Militant group Islamic Jihad said its fighters responded to the incursion with "four mortar shells," but made no mention of rocket fire, and did not specify where the shells had hit.
Rival Islamist group Hamas, which runs the territory's administration, detained two of the fighters and held them for hours before releasing them, an Islamic Jihad spokesman said.
Hamas has endeavoured to enforce a year-old Egyptian-brokered truce with Israel which ended the last major outbreak of fighting in and around Gaza late last year.
Thousands of members of Hamas' armed wing, the Ezzedine al-Qassam Brigades, today paraded in the Gaza Strip to mark the anniversary of that fighting, named Operation Pillar of Defence by the Israelis.
Across Gaza, hundreds of masked militants paraded in pick-up trucks, some with anti-aircraft guns and rocket launchers.
Senior Hamas official Mahmoud Zahar, accompanied by premier Ismail Haniya, gave a speech to thousands of fighters in which he talked of a "war of the tunnels".
