Syrian casualties treated in Turkey show signs of being victims of chemical weapons, the Turkish foreign minister said Friday, adding to indications that President Obama’s “red line” on the use of such arms may have been crossed.

Wary of the false intelligence used to justify the 2003 war in Iraq, the United States says it wants proof that chemical weapons have been used before taking any action in Syria.

Turkey confirmed last week it was testing blood samples from Syrian casualties brought over the border.

“We have some indications regarding chemical weapons being used, but in order to make sure and verify, we are continuing these tests and will be sharing these tests with U.N. agencies,” Foreign Minister Ahmet Davutoglu said in the Jordanian capital, Amman, on Friday.

Meanwhile, 25 people were killed when the army shelled the central Syrian town of Halfayeh on Friday, opposition activists said. Video posted on the Internet showed panic-stricken residents attempting to cross a river to escape the bombardment.

U.N. High Commissioner for Human Rights Navi Pillay said Friday she was concerned by reports of a major military buildup by army and pro-Assad militia members around the town of Qusair, near the Lebanese border.

Pillay said residents in Qusair feared a possible repeat of last week’s events in the coastal village of Baida and the town of Baniyas in which activists said more than 100 people were killed in a government advance.

“I am appalled at the apparent killing of women, children and men . . . which seem to indicate a campaign targeting specific communities perceived to be supportive of the opposition,” Pillay said.

— Reuters