A German teenage girl captured by Iraqi troops after she joined terror group Isis could still be sentenced to death, Iraq's prime minister has confirmed.

Linda Wenzel, 16, fled her home in Dresden, eastern Germany, more than one year ago. She was captured by Iraqi forces from the rubble in the city of Mosul in July as troops advanced in the besieged city to recapture it from Isis.

"You know teenagers under certain laws, they are accountable for their actions especially if the act is a criminal activity when it amounts to killing innocent people," Prime Minister Haider al-Abadi told AP.

It is believed that Wenzel, whom Iraqi troops accuse of being a sniper for Isis, was found along with other women who had joined the group in recent years. She is now in a prison in Baghdad.

It is not clear yet whether Wenzel can return to her home or must face trial in Iraq, where she could face the death penalty as per the country's counter-terrorism law. However, she would not be executed until the age of 22.

Iraqi intelligence officials told AP the girl worked for Isis police unit. However, her role within Isis will emerge following adequate investigation and a trial.

German officials have been engaging with the Iraqi government and said, earlier this month, they were confident the girl would be spared the death penalty, although she would face a long jail term in Iraq, Der Spiegel magazine reported.

Lorenz Haase, a senior public prosecutor in Dresden, told German media following the girl's arrest: "We, as the public prosecutor's office in Dresden, have not applied for an arrest warrant and will therefore not be able to request extradition.

"There is the possibility that Linda might be put on trial in Iraq. She might be expelled for being a foreigner or, because she is a minor reported missing in Germany, she could be handed over to Germany."

Following her capture, which was documented by footage that was largely shared on social media, Wenzel was interviewed by the German press in the infirmary of a military complex in Baghdad.

The girl said she had regretted her decision to join Isis and was willing to cooperate with authorities.

"I just want to get away from here. I want to get away from the war, from the many weapons, from the noise. I just want to go home to my family," she was quoted by the local press as saying.

A soldier who took part in Wenzel's capture told the Telegraph that Wenzel had married a Chechen Isis fighter, with whom she was found in Mosul. The fighter died during an exchange of fire with troops.

"She was a Daesh sniper, but maybe her husband pressured her into it," the soldier claimed, adding that the girl had admitted to having killed Iraqi soldiers.

It has also been claimed that the girl was found with a malnourished baby boy. A source within the Iraqi special operations forces (Isof) told The Sunday Times that Wenzel "keeps him with her always" and that she is producing breast milk, which suggested she is the mother of the infant.

Isis used to control larges swathes of Iraq and Syria, but the group has progressively lost several of its areas after joint offensives were launched against it in both countries.

The terror group seized Mosul in 2014. The city soon became one the group's strongholds in the Middle East. In July, the Iraqi army declared Mosul liberated from Isis after months of fierce fighting.