A former prisoner spearheading a private effort to help find captive US journalist Austin Tice is concerned that deposed Syrian leader Bashar al-Assad may be hiding him to use as leverage in securing his own future.

Nizar Zakka, who was detained in Iran on spying charges between 2015 and 2019, now runs Hostage Aid Worldwide, a non-profit group working with families to free kidnapped civilians.

This week he was in Syria in the immediate aftermath of the overthrow of Assad.

Governments worldwide are stepping up efforts to engage with Syria's new interim rulers, just over a week after Islamist-led rebels ousted president Bashar al-Assad, ending decades of brutal rule and civil war.

The lightning offensive that captured the capital Damascus on December 8 led to celebrations across the country and beyond.

At Damascus university on Sunday, Yasmin Shehab told AFP that she and fellow students felt "optimistic".

"We feel liberated, and the chains have been broken," she said. "Fear has been shattered."

Gaza's civil defence agency said Israeli strikes across the Palestinian territory on Sunday killed at least 40 people, including several children, an Al Jazeera TV cameraman and three rescuers.

Qatar-based news channel Al Jazeera said its cameraman Ahmed al-Louh was killed "in an Israeli bombardment" that targeted Nuseirat refugee camp in the central Gaza Strip.

Civil defence spokesman Mahmud Bassal confirmed Louh was killed in the strike that "targeted the Civil Defence site" in Nuseirat camp, also killing three members of the rescue agency.

Finally home in Turkey, Mehmet Erturk cannot eat the bread his wife has made him. After 20 years jailed in Syria, half his teeth are missing and the other half are threatening to fall out.

"It was torture after torture," he told AFP, miming the truncheon blows to the mouth the guards would give him at a notorious Damascus prison known as the Palestine Branch, where he spent part of his time incarcerated.

This time he was there by choice. Mohammed Darwish was back in a jail that was run by Syria's feared intelligence services -- and Bashar al-Assad was no longer president.

Cell number nine reeks of putrefaction. It is an underground windowless room with blackened dripping walls where the 34-year-old journalist was held with around 100 others.

Darwish was detained for months by one of the most feared branches of the former government's many-tentacled intelligence services.

Thousands of Israelis demonstrated Saturday for a deal to release the remaining hostages still held in Gaza after more than 14 months of war against Hamas in the Palestinian territory.

"We all can agree that we have failed until now and that we can reach an agreement now," Lior Ashkenazi, a prominent Israeli actor, told a crowd gathered in the commercial hub of Tel Aviv.

Itzik Horn, whose sons Eitan and Iair are still being held captive in Gaza, said: "End the war, the time has arrived for action and the time has arrived to bring everyone home."

The Syrian military intelligence officers who detained Ghazi Mohammed al-Mohammed told him to forget his name and who he was.

They took away his papers, he said, and told him: "Now you're number 3006."

For five and a half months Mohammed languished in one of president Bashar al-Assad's jails, losing 40 kilograms (88 pounds), all the while under the threat of imminent execution.

Lebanese Prime Minister Najib Mikati called Saturday for Syrians who sought refuge in his country to return home following the fall of Syria's longtime leader, Bashar al-Assad.

"The consequences of the Syrian war made Lebanon home to the largest number of refugees per capita, with one-third of our population comprising of Syrian refugees", Mikati said at a Rome political festival.

"The strain on our resources has been substantial, worsening existing economic trouble and creating fierce competition for jobs and services," he said in English.

Gaza's civil defence agency said Israeli strikes on the territory killed 17 people on Saturday, including seven at a UN school housing displaced people that the Israeli military said was used as a Hamas command centre.

Civil defence spokesman Mahmud Bassal told AFP there were seven people killed, including women and children, and at least 10 wounded "when Israeli warplanes targeted the Al-Majida Wasila school west of Gaza City".

The United States has made "direct contact" with Syria's victorious Hayat Tahrir al-Sham rebels despite designating the group as terrorists, Secretary of State Antony Blinken said Saturday, as he sought international unity on a peaceful transition.

"We've been in contact with HTS and with other parties," Blinken told reporters after talks on Syria in the Jordanian Red Sea resort of Aqaba.

He did not give details on how the contact took place but when asked if the United States reached out directly, he said: "Direct contact -- yes."