IDIL, Turkey (Reuters) - Turkish police stopped pro-Kurdish politicians on Thursday marching to a town where they say 21 civilians have been killed and a humanitarian crisis has unfolded since authorities imposed a curfew to combat Kurdish rebels.
Turkish authorities said nearly all of those killed in the week-old curfew were Kurdish militants.
Cizre, near Turkey's borders with Syria and Iraq, has become a flashpoint in two months of deepening violence in the mainly Kurdish southeast. Hundreds have died since Kurdistan Workers Party (PKK) militants and the state resumed hostilities after the collapse of ceasefire in July.
Lawmakers from the Peoples' Democratic Party (HDP), which draws most of its support from Kurds, say civilians in the town, which has more than 100,000 inhabitants now under a round-the-clock curfew because of the fighting, are in a dire situation, with the dead going unburied and food and water running short.
The unrest in southeastern territories coincides with advances by jihadists, including Islamic State, across the border in Syria and Iraq. Turkey has launched air attacks against Islamic State targets in Syria and PKK bases in Iraq.
Like Turkey, the United States and European Union consider the PKK - which launched a separatist insurgency three decades ago - a terrorist organization. But Turkey's NATO allies have counseled caution on Ankara in dealing with the PKK, wary escalating violence could undermine stability of a key partner.
Interior Minister Selami Altinok said operations by security forces had killed more than 30 militants since last week and led to the seizure of 800 kg (1,800 pounds) of explosives.
He said only one civilian had died in the town.
Some 30 HDP parliamentarians, including leader Selahattin Demirtas, started a 90-km (55-mile) march on Wednesday towards Cizre after security forces halted their convoy, the party said.
The group, which returned to the nearby town of Idil after staging a brief sit-down protest, included European Union Minister Ali Haydar Konca and Development Minister Muslum Dogan, members of an interim cabinet leading Turkey to a Nov. 1 election.
The HDP has accused President Tayyip Erdogan and the ruling AK Party of using the bloodshed to whip up nationalist sentiment ahead of the vote. Both sides have questioned how a fair election can take place in such conditions.
HDP offices have been attacked, some set ablaze, by nationalist crowds this week.
"What is under way in Cizre, a blockade of the town and a seven-day curfew, is completely illegal," said one of the HDP lawmakers, Saruhan Oluc, adding 100,000 people faced food shortages and the wounded were unable to reach hospital.
"This is a humanitarian crisis."
Altinok said the politicians had been prevented from reaching Cizre for their own safety.
"We evaluated that their arrival in Cizre may cause provocative events, so it's out of the question for them to go there," he told a news conference.
Guards opened fire on hundreds of men wading across a river between Turkey and Iraq after they were stranded on the Iraqi side when the border crossing was shut, video footage showed. Four of the men, all of whom were truck drivers, were wounded by the gunfire, Dogan News Agency said.
"We have been waiting for a week without word from our family, our children. They won't allow us to enter at the gate so we had to cross the border here," one man told the agency.
The HDP said eight of 21 civilians who had died in Cizre had been killed since Wednesday night alone.
Unable to transport the dead, families were using deep freezers to preserve corpses, Cumhuriyet newspaper said.
HDP lawmaker Sibel Yigitalp, who was in the town, tweeted photographs of a blood-soaked dead mother and her crying infant.
"There is a serious shortage of food, water, access to basic health services, preventative treatment of the wounded, and burial of those who have been killed by state security forces," the HDP said in a statement. Phone lines were also being cut and access blocked to the media, it said.
Prosecutors in Diyarbakir, the region's largest city, launched investigations into Demirtas on Wednesday on charges of terrorist propaganda and insulting the president, requesting that his parliamentary immunity be lifted.
Erdogan has repeatedly accused the HDP of militant links.
"If you take the side of terror you run the risk of paying the price," he said on Wednesday.
Additional reporting by Ayla Jean Yackley in Istanbul and Gulsen Solaker in Ankara; Writing by Daren Butler and David Dolan; Editing by Nick Tattersall and Andrew Roche