A three-day truce collapsed Friday in a new round of violence after Gaza militants resumed rocket attacks on Israel, drawing a wave of retaliatory airstrikes that killed at least five Palestinians, including three children.

The eruption of fighting shattered a brief calm in the month-long war and dealt a blow to Egyptian-led efforts to secure a long-term ceasefire between the bitter enemies.

A delegation of Palestinian negotiators remained in Cairo in hopes of salvaging the talks. But participants said the negotiations were not going well, and Israel said it would not negotiate under fire. The Palestinian delegation met again late Friday with Egyptian mediators.

Azzam al-Ahmad, head of the Palestinian delegation, said the delegation would stay in Egypt until it reaches an agreement that "ensures" the rights of the Palestinian people. "We told Egyptians we are staying," he told reporters.

The indirect talks are meant to bring an end to the deadliest round of fighting between Israel and Hamas since the Islamic militant group seized control of Gaza in 2007. In four weeks of violence, more than 1,900 Gazans have been killed, roughly three-quarters of them civilians, according to Palestinian and UN officials. Sixty-seven people were killed on the Israeli side, including three civilians.

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It's not yet clear how renewed fighting will impact ongoing truce negotiations in Cairo. (Ahmed Zakot/Reuters)

The Palestinians are seeking an end to an Israel-Egyptian blockade imposed on Gaza after the Hamas takeover. Militants had warned they would resume fighting after the ceasefire expired unless there was a deal to ease the restrictions.

The blockade, which Israel says is needed to prevent arms smuggling, has constrained movement in and out of the territory of 1.8 million people and brought Gaza's economy to a standstill.

Israel says any long-term agreement must include guarantees that Hamas, an armed group sworn to Israel's destruction, will give up its weapons.

Cairo talks off to poor start

In Cairo, Palestinian participants in the talks were pessimistic about the chances of a deal. They said Israel was opposing every Palestinian proposal for lifting the blockade.

For instance, the Palestinians are seeking greater movement of goods through Israeli-controlled cargo crossings, while Israel wants restrictions on "dual-use" items that could potentially be used for military purposes, they said.

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Israel launched air strikes across the Gaza Strip on Friday in response to Palestinian rockets fired after Egyptian-mediated talks failed. (Abed Omar Qusini/Reuters)

Israel also was resisting demands to allow movement between Gaza and the West Bank -- Palestinian territories that are located on opposite sides of Israel, they said.

"Israel in these talks wants to repackage the same old blockade. Our demands are ending the blockade and having free access for people and goods. This is what ending the blockade means. But Israel is not accepting that," said Bassam Salhi, a Palestinian negotiator.

Negotiators said they expected to remain in Cairo for several days. But with violence resuming, it was unclear how much progress could be made.

The Israeli delegation to the Cairo talks left Egypt on Friday morning, and it was not clear if it would return. "There will not be negotiations under fire," Israeli government spokesman Mark Regev said.

UN disappointed at ceasefire's failure

In Cairo, Khaled al-Batch, a leader of Islamic Jihad, a smaller militant group in Gaza, said that without a deal on easing the blockade, an informal truce might be the best that could be achieved.

"When there is no ceasefire, that does not mean there is escalation," he said. "Our priority now is to focus on stopping the Israeli aggression against our people and achieving our demands."

Egypt's Foreign Ministry urged restraint by both sides and called for a new cease-fire to resume negotiations. The ministry said progress had been made in the talks but did not explain.

UN Secretary-General Ban Ki-moon expressed "deep disappointment" at the failure to extend the ceasefire and urged the parties to swiftly find a way back to the negotiating table, UN deputy spokesman Farhan Haq said.

The original, three-day truce expired at 8 a.m. Friday. But Gaza militants began firing rockets even before then. By late Friday, nearly 60 rockets had been fired. Two Israelis were hurt, and one of the rockets damaged a home.

Israel responded with a series of airstrikes. Palestinian officials said at least five people were killed in three separate strikes, two of them near mosques. Among the dead were three boys, a 10-year-old and two cousins, aged 12. At least five boys were wounded.

The deaths brought the overall Palestinian toll since July 8 to 1,902, said Palestinian health official Ashraf al-Kidra.   

Hamas entered the Cairo talks from a position of military weakness, following a month of fighting in which Israel pounded Gaza with close to 5,000 strikes. Israel has said Hamas lost hundreds of fighters, two-thirds of its rocket arsenal and all of its tunnels under the border with Israel. Egypt has destroyed a network of smuggling tunnels that was once Hamas' economic and military lifeline.

With files from Reuters