In war-torn Syria, parents of teenagers missing in a shipwreck off the Greek coast are clinging onto hope their children might be alive, days after the tragedy.

A fishing boat overloaded with migrants capsized and sank off Greece's Peloponnese peninsula on Wednesday, killing at least 78 people.

While the exact number of passengers on the rusty trawler is unknown, hundreds are feared missing, and relatives and activists have told AFP at least 141 Syrians were aboard.

Iyad from Jassem in the southern province of Daraa, the cradle of Syria's 12-year civil war, said his 19-year-old son Ali was still unaccounted for.

"I have had no news of my son. I haven't spoken to him. I haven't heard his voice," said Iyad, who works at a school and declined to provide his surname.

"His mother hasn't stopped crying for three days."

The 47-year-old said he had heard of two Greek reports -- one listing his son among the survivors and another among the dead.

"I still have hope that he will be among the survivors," Iyad told AFP by telephone on Saturday. "We are praying to God day and night."

- A better life -

The teenager was looking for a better life in Libya, his father said, and had travelled there by plane from Damascus.

"He told us he wanted to work in a restaurant" and had planned to send money to help the family, Iyad added.

"We didn't know he wanted to take a boat," he said. "If we'd known, we wouldn't have allowed him to go."

Activists at the Daraa Martyrs Documentation Office told AFP on Saturday that 106 people aboard the trawler were from the country's south, mainly from Daraa province, where they said "living and security situation... is absolutely unbearable".

Only 34 so far were known to have survived, they added.

A blind 15-year-old boy and his 28-year-old sister from Daraa province were also among those missing, their uncle told AFP on Friday, declining to be identified for security reasons.

Daraa province was the cradle of the 2011 uprising against Syrian President Bashar al-Assad, but it returned to regime control in 2018.

Iyad said Ali's uncle in Germany had travelled to Greece to search for the boy, but "it's like looking for a needle in a haystack".

"For us, he is missing. We have not mourned and we will not mourn until we are sure what has happened," he said.

"If he is found alive, we'll bring him back to Syria. I don't want my son to be far away from me... not even for one more second.

"We borrowed a large amount of money to send him to Libya to work -- not to die."

- 'Fleeing death, finding death' -

In Kobane in Syria's Kurdish-held north, Mohammed Mohammed said he too was awaiting news of the fate of his 15-year-old son Diyar.

"Every day, hope is fading of seeing my son again," Mohammed, a tyre repairman, told AFP by telephone late Friday.

Diyar "left because the situation here is terrible", the 48-year-old said.

Kobane became a symbol of symbol of victory over the Islamic State group, after US-backed Kurdish forces drove the jihadists out in 2015.

But the city, also known as Ain al-Arab, is in the crosshairs of Ankara, which wants Kurdish forces to withdraw from frontier areas.

Turkey has carried out deadly raids in the area and threatened a new ground offensive.

Mohammed said the family lived less than one kilometre (little more than half a mile) from the Turkish border.

Diyar's "dream was to go to Germany to be with my brother who lives there", he said.

"Everyone wants to leave," he said, adding Diyar had been with four friends.

At least 35 people aboard the boat were from Kurdish-held areas in Syria's north, a relative told AFP on Friday.

Mohammed said his brother had travelled to Greece in the hope of finding Diyar, but was denied entry to hospitals where he had hoped to speak to survivors.

"People are fleeing death, but finding death" along the way, he said.