A leading international watchdog has accused the militant Hamas group of abducting, torturing and killing Palestinians during the war in the Gaza Strip last year, saying some of the actions amount to war crimes.

Amnesty International detailed the abuses in a report entitled Strangling Necks: Abduction, torture and summary killings of Palestinians by Hamas forces during the 2014 Gaza/Israel conflict.

According to the London-based human rights group, 23 Palestinians were shot and killed and dozens more arrested and tortured by Hamas, which rules Gaza.

The Palestinians targeted were either political rivals of Hamas, including members of the Fatah party of Palestinian president Mahmoud Abbas, or people the militant group had accused of co-operating with Israel, Amnesty said.

The report highlighted a particularly brutal incident, which it said took place in Gaza on August 22.

"In one of the most shocking incidents, six men were publicly executed by Hamas forces outside al-Omari mosque ... in front of hundreds of spectators, including children," Amnesty said.

Hamas had announced the men were suspected "collaborators" who had been sentenced to death in "revolutionary courts", the rights group added.

"The hooded men were dragged along the floor to kneel by a wall facing the crowd, then each man was shot in the head individually before being sprayed with bullets fired from an AK-47," the report said of the August incident.

Hamas violently seized Gaza from forces loyal to Mr Abbas in 2007, leaving Palestinians bitterly divided - Hamas ruling Gaza and Mr Abbas governing parts of the West Bank.

Since then, Hamas has launched thousands of rockets at Israel and fought three wars with the Jewish state. More than 2,200 Palestinians were killed during the 50-day war last summer. On the Israeli side, 67 soldiers and six civilians were killed.

Hamas used the war to "ruthlessly settle scores, carrying out a series of unlawful killings and other grave abuses", Amnesty's Philip Luther said. "These spine-chilling actions, some of which amount to war crimes, were designed to exact revenge and spread fear across the Gaza Strip."

The report said 16 of the people killed by Hamas were already being held by the militant group when the conflict erupted and many were waiting to hear the verdict of their Hamas-organised trials.

"Many had been sentenced after trials before courts whose proceedings are grossly unfair. A number had said they had been tortured in order to extract 'confessions'," the report said.

Amnesty's report also said Hamas abducted and tortured people in an outpatient clinic that was no longer in use, within the grounds of Gaza City's main hospital, Shifa.

"Hamas forces have displayed a disregard for the most fundamental rules of international humanitarian law," Mr Luther said. "Torture and cruel treatment of detainees in an armed conflict is a war crime. Extrajudicial executions are also war crimes."

This was not Amnesty's first report on the 2014 Gaza war.

In March, the group accused Hamas of war crimes for launching unguided rockets and mortars from civilian areas in Gaza towards civilian areas in Israel, saying that was a breach of international law. And in December, Amnesty condemned Israel for flattening four landmark buildings in the final days of the war. Israel dismissed that report, saying Hamas was using the buildings as command centres.

Salah Bardawil, a Hamas official in Gaza, said the incidents mentioned in the report took place "outside the framework of the law" and Hamas was investigating them.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.