Negotiators in Cairo have addressed the issue of the Israeli Gaza blockade , as the clock ticks down to the 2100 GMT deadline that will end a current 72-hour truce.

By that time on Wednesday, Israeli and Palestinian negotiators in the Egyptian capital must have either agreed on a permanent ceasefire, accepted an extension or risk a resumption of more than a month of bloody fighting.

As Gaza's residents ventured out into the quiet to try to piece together their battered lives, negotiators held a second round of indirect talks aimed at finding a durable end to the five-week confrontation.

A senior Israeli official told the AFP news agency there was still a long way to go to agree an end to the conflict, which erupted on July 8 when Israel launched military operations to halt cross-border rocket fire from Gaza.

"The negotiations are difficult and grueling," a Palestinian official said of Monday's opening talks, which lasted almost 10 hours and which were described as "serious".

Tuesday's talks, which opened during the afternoon and tackled core issues such as Israel's eight-year blockade of Gaza, went on late into the night.

Earlier on Tuesday, an Israeli official played down the chances of success.

"The gaps are still very wide. There has not been progress in the negotiations," he told AFP.

Hamas, the Palestinian group which runs Gaza, wants Israel to lift the blockade it imposed on the enclave in 2006 before it will stop rocket attacks. Israel has said it will only facilitate Gaza's reconstruction if the enclave is fully disarmed.

In a sign that Israeli Prime Minister Benjamin Netanyahu faced domestic political battles to sell any deal to his fractious coalition government, he called off a planned meeting of his security cabinet on Tuesday.

Hamas tunnels

This is the second 72-hour ceasefire to be held during the conflict. The first only came about after Israel announced it had completed the destruction of a network of Hamas tunnels that crossed the blockade.

Israel is now preparing to build a network of sensors to try to detect tunnel building into its territory from the Gaza Strip, but it could take months to prove the technology works, a senior army officer told the Reuters news agency.

In the meantime, the army might re-invade the Palestinian enclave to destroy any tunnels it discovers or that it thinks are under construction, another official said, looking to calm the fears of Israelis living close to the Gaza border.

The army said it destroyed 32 tunnels last month, but believes some, which also serve as bunkers and weapons caches, survived intact.

After more than a decade of failed attempts to develop ways to reveal the infiltration tunnels, an army officer said the military was preparing to place sensors around Gaza's perimeter.

The army hopes these will not only be able to detect tunnels under construction, but also others already built.

In a briefing to reporters, the officer, who declined to be named, said the sensors would be augmented by physical obstacles placed along the 68 km-long (42 miles) frontier.

He did not discuss the technology, but said testing over the next few months would show whether it was ready for use. Previous experimentation has focused on seismic detectors.

PHOTO CAPTION

Israeli soldier on a Armored Personnel Carriers (APC) ready their gear in a staging area, very close to the Gaza Strip border, in southern Israel, 27 July 2014.

Aljazeera