Iraqi courts are sending alleged Islamic State (IS) fighters to death in rapid-fire trials lasting less than 20 minutes, according to reports.

It comes amid concerns from human rights groups that innocent people are among thousands being detained or sent to the gallows under counterterrorism laws following rushed investigations and flawed court hearings.

In one trial, reported in the Washington Post on Thursday (28 December), two Turkish men were brought into a Baghdad courtroom to face charges of belonging to IS.

The pair – Ramadan Hassan, 24, and Talat Yakout, 40 – denied being members of the terror group, saying they were simply plumbers who migrated to Iraq looking for work.

They claimed a confession read out in court came only after they were tortured.

They were sentenced to death by hanging after a trial that lasted just 18 minutes earlier this month.

The men are among thousands of IS suspects that have been captured, detained and put on trial as the Sunni Muslim terror group's self-proclaimed caliphate crumbles following defeats in Iraq and Syria.

This reportedly includes hundreds of foreigners – men, women and children – from Asia, Europe and Africa, with their home countries expressing little desire to repatriate them.

In what Prime Minister Haider al-Abadi said would offer comfort to IS victims, Iraq has been fast-tracking executions of alleged fighters as it repairs the damage done to the country after liberating towns and cities from the terror group's rule.

Iraq's Justice Ministry said there had been 194 terrorism-related executions since 2016, the Washington Post reported. Up to 6,000 more are reportedly on death row.

But the swift justice approach has already led to concerns, including from the United Nations, of serious judicial and human rights violations.

Earlier this month, a Human Rights Watch report accused Iraq of "serious legal shortcomings that undermine efforts to bring (Islamic State) fighters, members, and affiliates to justice."

This included the country's authorities using "overbroad" counterterrorism laws to allow easier convictions of suspects, rather than bringing criminal charges for specific crimes.

The process is also said to be failing to distinguish between those who embraced IS and others who were coerced to cooperate through fear of being killed by the group's fighters.

Those who worked in IS-run hospitals or kitchens were also being handed the same sentence as alleged fighters, with one senior counterterrorism judge telling HRW: "I had a case yesterday of an Isis cook and I have recommended giving him the death penalty. How could the Isis fighter have executed someone if he had not been fed a good meal the night before?"

Detainees have also alleged that Iraqi authorities use torture to illicit confessions of IS membership, and that they are not granted lawyers.

Others said they had been held in overcrowded centres for months on end after being detained simply because the authorities believe malicious accusations from members of their community with personal vendettas.

In responding to the HRW report, Prime Minister Haider al-Abadi denied that his country puts IS suspects on trial without evidence. He did not respond to the other accusations levelled in the report.