Alarm has grown over the humanitarian situation in Kurdish-majority Cizre, a city of 120,000, as the army pursues an operation to eliminate Kurdistan Workers Party (PKK) militants in the city.

The government has said it intends to keep the curfew in place as long as needed and refused to let a delegation of opposition MPs enter Cizre.

"Normally, the fine when someone breaks a curfew is 100 Turkish Lira ($33)," said Selahattin Demirtas, the co-chairman of the pro-Kurdish Peoples' Democratic Party (HDP) who has been trying to visit the city in the last days.

"In Cizre, the fine is the death sentence and executions," Turkish media quoted him saying in the town of Idil west of Cizre.

Interior Minister Selami Altinok said Thursday that up to 32 PKK militants had been killed in Cizre, adding just one civilian had been killed in clashes.

The HDP however contends that the civilian death toll is 21, including children.

"Those who venture out into the streets are killed by snipers. A violation that normally costs just 100 Lira has become the price of death for the Kurds," Demirtas added.

Demirtas challenged the authorities to give names and prove that a single one of those killed were members of the PKK.

"We don't even know if there are armed militants there, we can't go inside," he added.

He said that Altinok and the governor of Sirnak province where Cizre is located Ali Ihsan Su should be brought to justice.

"You can explain in court how you gave the order for the executions."

The Firat news agency, seen as close to the PKK, claimed that two youngsters aged 10 and 15 were shot dead overnight for breaking the curfew. There was no official confirmation of the report.

Council of Europe Commissioner for Human Rights, Nils Muiznieks expressed alarm over the "very distressing information" from Cizre, urging that independent observers be allowed into the city.

He said the situation "combines an exceptionally severe interference with the human rights of a very large population and a near-complete information blackout".

The operation in Cizre is a key part of the government's relentless drive to cripple the PKK in southeast Turkey and northern Iraq, which started in late July and shows no sign of abating.