Israel and Palestinian militant group Hamas have raised concerns over the lists of Israeli hostages and Palestinian prisoners due to be released on Monday, the final day of an agreed four-day pause in the fighting, an official briefed on the matter said.

The official, speaking on condition of anonymity, told Reuters that Qatari mediators were working with Israel and Hamas to resolve the issues and avoid delays.

Hamas said it wanted to extend the truce. An Israeli official reiterated on Monday Israel's position that it would agree to an additional day of truce for each additional 10 hostages freed and to release three times the number of Palestinians each time.

"There is a slight issue with today’s lists. The Qataris are working with both sides to resolve it and avoid delays," the official briefed on the matter said.

Israel said earlier it had received overnight what could be the final list of hostages due for release. The list was being reviewed, Prime Minister Benjamin Netanyahu's office said, adding it would provide further information when possible.

On Sunday, Hamas freed 17 people, including a 4-year-old Israeli-American girl, bringing the total number the militant group has released since Friday to 58. Israel released 39 teenage Palestinian prisoners on Sunday, taking the total number of Palestinians freed since the truce began to 117.

An Israeli government spokesperson said on Monday that the total number of hostages still held in Gaza was now 184, including 14 foreigners and 80 Israelis with dual nationality.

A Palestinian official, familiar with the truce talks, said both Hamas and Israel had shown a positive attitude to requests to extend the four-day pause in fighting, but added that "a final decision hasn't yet been reached".

Qatar, Egypt, the United States, the European Union and Spain were all working to extend the ceasefire, the Palestinian Authority's foreign minister, Riyad al-Maliki, said during a conference in Barcelona devoted to the crisis.

An Israeli official told Reuters the onus was on Hamas to produce a new list of 10 hostages it could free on Tuesday in exchange for that becoming an additional truce day. That process would continue for a maximum of five additional days to the current truce, the official added.

Hamas spokesperson Osama Hamdan, speaking to Lebanon's LBC broadcaster, said the group would try to find more hostages to release and thus prolong the truce. Hamas has previously said it is not holding all the hostages who were brought to Gaza.

The people handed over by Hamas on Sunday included 13 Israelis, three Thais and one with Russian citizenship, and the International Committee of the Red Cross confirmed it had successfully transferred them from Gaza.

'CAN'T BELIEVE I'M FREE'

The truce agreed last week is the first halt in fighting in the seven weeks since Hamas attacked Israel, killing 1,200 people and taking about 240 hostages back into Gaza.

In response to that attack, Israel has bombarded the enclave and mounted a ground offensive in the north. Some 14,800 Palestinians have been killed, Gaza health authorities say, and hundreds of thousands displaced.

Palestinians gave the freed prisoners a jubilant reception in Ramallah, according to Palestinian news agency WAFA.

Omar Abdullah Al Hajj, 17, released on Sunday, told Reuters he'd been kept in the dark about what was happening in the outside world.

"We were 11 people crammed into a single room where usually there are six. There was never enough food and I was never told how long I was going to stay," he said.

"I can't believe I'm free now but my joy is incomplete because we still have our brothers who remain in prison," said Al Hajj, whom Israel's Justice Ministry accused of belonging to the Islamic Jihad militant group and posing a security threat which it did not specify.

Palestinians in Gaza said on Monday they were praying for an extension of the truce. Some were visiting homes reduced to rubble by weeks of intensive Israeli bombardment, while others queued for flour and other essential aid being delivered by the United Nations' relief agency UNRWA.

The Al Sultan family, among hundreds of thousands of people displaced from their homes in the north of the Gaza Strip, snatched a few hours of sorely needed relaxation by the sea.

"We used these four days (of truce) and came to the beach in Deir Al-Balah to allow our children to have some fun," their mother, Hazem Al Sultan, said. "We are anticipating the end of these four days, and we don’t know what will happen to us next."

As it pummelled Hamas targets in the northern Gaza Strip in recent weeks, Israel had urged residents to head south, but some have stayed put, including a few doctors and nurses at Gaza City's Kamal Edwan medical complex tending to patients including children who they said cannot be moved.

"The situation here is very bad, we don't have food, drink, or any other needs for life or even medical supplies," said nurse Hashem Abu Warda.

EU APPEAL

The European Union's top diplomat, Josep Borrell, said on Monday the truce was an important first step but that far more would be needed to alleviate the situation.

Speaking at the Forum for the Union of the Mediterranean in Barcelona, Borrell also urged Israel not to "recolonise Gaza", saying that the creation of a Palestinian state in the West Bank, East Jerusalem and Gaza was the best guarantee of Israel's peace and security.

Al-Maliki of the Palestinian Authority, which runs the occupied West Bank, told the Forum that the international community must pressure Israel to extend the truce indefinitely. The death toll would double if war resumes on Tuesday, he added.

Netanyahu said at the weekend that once the truce ends "we will return with full force to achieve our goals: The elimination of Hamas, ensuring that Gaza does not return to what it was; and of course the release of all our hostages."