BEIRUT (AP) — A top official with Palestinian President Mahmoud Abbas’ Fatah group said Sunday that Palestinian and Lebanese officials have given militant Islamic groups in Lebanon’s largest Palestinian refugee camp until the end of the month to hand over the accused killers of a Fatah general.

A fragile calm has largely prevailed in the Ein el-Hilweh camp since Thursday night after the warring sides reached the latest in a series of cease-fire agreements. It followed a week of intense fighting that killed at least 18 people and wounded and displaced hundreds.

Top officials from rival Palestinian groups Fatah and Hamas had traveled to Lebanon in an attempt to negotiate an end to the clashes.

Azzam al-Ahmad, a member of Fatah’s central committee and of the Executive Committee of the Palestine Liberation Organization, said in an interview with The Associated Press on Sunday that he is “optimistic about reaching a solution.” But, he added, if the accused are not handed over by the end of the month, “all possibilities are open.”

Al-Ahmad said Fatah is not opposed to the Lebanese army entering the camp to conduct an operation against the militant Islamic groups should they not turn over the men accused of killing Fatah military general Mohammad “Abu Ashraf” al-Armoushi.

By tradition, Lebanese soldiers do not enter the Palestinian camps, which are controlled by a network of Palestinian factions. The last time Lebanon’s army intervened in one of the camps was in 2007, when it battled Islamic extremists in the Nahr al-Bared camp in north Lebanon, razing most of it in the process.

Hamas, which rules Gaza, has officially stood on the sidelines in the clashes between Fatah and a number of extreme Islamic groups in the camp, but al-Ahmad accused Hamas members of taking up arms against Fatah “in some areas of fighting,” an accusation that Hamas has denied.

Senior Hamas official Moussa Abu Marzouk, who last week met with Lebanese officials and representatives from the Palestinian factions to try and reach a settlement to end the clashes, said in a message via the WhatsApp messaging application that “we were not involved in the shooting at all” and that “there have been continuous efforts” by Hamas to broker a “cease-fire agreement in any form.”

“It is clear that clashes do not make anyone hand over anyone,” he said. “... No one is willing to give himself up in the shadow of war.”

Hamas spokesman in Lebanon Walid Kilani denied that a specific deadline had been set for handing over the killers.

“What was agreed upon there will be the formation of a joint security force that includes all Palestinian factions” to implement the handover of people “wanted by both sides,” he said.

Both Fatah and Hamas have accused external forces of stoking the violence in the camp, which is home to more than 50,000 people, in an attempt to weaken the Palestinian cause. Marzouk described it as part of a “conspiracy against the Palestinian diaspora,” while al-Ahmad said the killing of Armoushi was “not only an assassination case, but a case of attempted removal of the Ein el-Hilweh camp.”

The United Nations agency for Palestinian refugees said Friday that 18 people had been killed and 140 injured in the latest round of clashes, which broke out Sept. 7.

Nearly 1,000 people displaced by the fighting were staying in emergency shelters set up by UNRWA while hundreds more were sheltering in at other sites, including a nearby mosque and in the courtyard of the municipality building of the city of Sidon, which is adjacent to the camp, or with relatives.

Earlier this summer, there were several days of street battles in the Ein el-Hilweh camp between Abbas’ Fatah movement and militant Islamic groups after attackers gunned down Armoushi and four of his companions July 30.

The assassination was apparently an act of retaliation after an unknown gunman shot at Islamist militant Mahmoud Khalil, killing a companion of his instead.

Those street battles left at least 13 dead and dozens wounded, and forced hundreds to flee from their homes.