Israel has stepped up its response to rocket strikes from the Gaza Strip, threatening a prolonged attack "without restrictions" on Palestinian militants.
Israel says Akram school, Gaza, raised funds for Hamas
Israeli aircraft launched a series of overnight air raids, injuring several people, and arrested more than 200 suspected militants in the West Bank.
The escalation of violence comes only a fortnight after Israel's military withdrawal from the Gaza Strip.
The EU said it was concerned and called for restraint on both sides.
The British presidency of the EU "calls on the Palestinian Authority to take all necessary steps to take full control of security in the Gaza Strip", it said in a statement.
"The Presidency recognises Israel's right to act in self-defence, but calls on Israel to act with restraint."
In the latest activity, Israeli forces launched air strikes early on Sunday against alleged weapon storage sites, and a school linked to the militant group Hamas. At least 19 people were reported injured in the strikes.
They are part of a cycle of violence over several days:
The Israeli army said those arrested in the West Bank included activists from both Hamas and Islamic Jihad.
- Friday: Israeli troops shoot dead three Islamic Jihad militants in Tulkarm, West Bank, in raids on those suspected of involvement in suicide attacks earlier this year
- Friday: Islamic Jihad responds with a rocket attack on Israel from Gaza
- Friday: An explosion at a Hamas rally in Gaza kills 15 people. Hamas blames Israel. Israel denies any involvement. The Palestinian Authority accuses Hamas of mishandling weapons at the rally
- Friday/ Saturday: militants fire up to 40 rockets from Gaza into Israel. Hamas calls them revenge for the rally blast
- Saturday: Israel launches a series of air raids in response, including one that kills two Hamas militants in a car in Gaza
- Saturday: Israeli troops and artillery gather on the border with northern Gaza. The borders with Gaza and the West Bank are sealed
- Saturday/ Sunday: Israel launches more overnight air strikes and arrests more than 200 Palestinians in West Bank
Hamas said Hassan Yousef, its leader in the West Bank, was among them.
Israeli Prime Minister Ariel Sharon told cabinet ministers on Sunday that he had ordered continuous military strikes in response to the rocket attacks on the Israeli town of Sderot, which injured at least five people.
"I have issued orders that there be no restrictions regarding the use of all means to strike at the terrorists, members of terrorist organisations, and their equipment and their hideouts," he said.
Khan Younis was also targeted in the latest raids
"We don't intend here to stage a one-time action, but intend to carry out a continued action, whose aim is to hurt the terrorists and not to let up."
Major General Yisrael Ziv, army head of operations, predicted "a prolonged and constant attack on Hamas".
Israeli forces planned to resume targeted killings of militants, officials told the Haaretz newspaper.
The BBC's Lucy Williamson in Jerusalem says Israel has not ruled out a ground invasion of Gaza.
The increased tension comes at a sensitive time for Israeli Prime Minister Ariel Sharon, our correspondent says.
He faces a party leadership challenge, with his Likud party's central committee due to vote on Monday whether to back his rival and former prime minister, Benjamin Netanyahu.
Mr Netanyahu opposed Mr Sharon's decision to pull settlers out of Gaza, saying it would encourage Islamic militants to attack Israel.
He is seeking the Likud leadership, with national elections a little over a year away.
If Mr Sharon loses the vote, it is thought he might leave the party and set up a new centrist alliance that polls suggest would be popular with voters.