Hamas fighters were set Sunday to release a third group of Israeli hostages in exchange for Palestinian prisoners, a day after freeing captives including a young woman snatched from a desert rave.

In a sign of the fragility of the exchanges, the latest swap Saturday was delayed for hours after Hamas accused Israel of breaching its side of the deal that led to a four-day ceasefire in the seven-week-old war.

Despite the dispute, Hamas finally released 13 Israelis and four Thai hostages at night, officials said.

Israel said it in turn freed 39 Palestinian prisoners.

The office of Israeli Prime Minister Benjamin Netanyahu said it had since received a list of hostages due to be released by Hamas on Sunday.

The list was being checked by security officials, it said, and families of the hostages had been informed.

Among the hostages freed late Saturday was 21-year-old Maya Regev, who had been kidnapped by Hamas fighters in their deadly assault on the Supernova music festival, a brutal episode in the broader October 7 attack on Israel.

She was the first of the music festival hostages to be released since armed Hamas fighters swooped on the event, killing hundreds, taking captives, and sending others fleeing for their lives.

Maya Regev and her 18-year-old brother Itay, who was also abducted from the festival, were shown tied up in the back of a pick-up truck in a video posted on social media after the attack.

"I am so excited and happy that Maya is on her way to us now. Nonetheless, my heart is split because my son Itay is still in Hamas captivity in Gaza," her mother Mirit said in a statement released by the hostage families' forum.

The family of Emily Hand, a nine-year-old Israeli-Irish freed hostage, said they were "overjoyed" to embrace her again.

"We can't find the words to describe our emotions after 50 challenging and complicated days," the family said in a statement via the forum.

"We are overjoyed to embrace Emily again, but at the same time, we remember... all the hundreds of hostages who have yet to return."

The girl ran into the tight embrace of her father upon her release, a video by the Israeli Defence Forces showed.

"An innocent child who was lost has now been found and returned, and we breathe a massive sigh of relief," said Ireland's Prime Minister Leo Varadkar.

Thailand's Prime Minister Srettha Thavisin said the four hostages from his country released Saturday were healthy.

"Everyone is glad to be released. Overall mental health is still good," he said in a social media post.

Israeli prison authorities said the latest group of released Palestinian detainees included 38-year-old Israa Jaabis, sentenced to 11 years in jail for detonating a gas cylinder at a checkpoint in 2015.

The ceasefire and hostage-for-prisoner swap have brought the first significant relief to both sides since October 7, when Hamas fighters broke through Gaza's militarised border with Israel, snatched around 240 people and killed about 1,200 Israelis and foreigners, according to Israeli authorities.

Israel launched an air, artillery and naval bombardment alongside a ground offensive to destroy Hamas, killing nearly 15,000 people, mostly civilians and including thousands of children, according to the Hamas government in Gaza.