Merkel blames Assad regime for Syria chemical attack
Merkel called the chemical attack, in which scores were killed, a "barbaric" act and a war crime.
"Unfortunately, there are elements showing that it came from the Assad regime," she told reporters late on Thursday.
Merkel called for an urgent investigation into the attack, which she said her country will be part of.
She also criticised the failure of the UN Security Council to pass a resolution condemning the attack, adding that those who refused to back the resolution "should think about what responsibility they are shouldering."
At least 86 people were killed early on Tuesday in rebel-held Khan Sheikhun, and dozens more treated for convulsions, breathing problems and foaming at the mouth.
World powers have pointed the finger at the government of Bashar al-Assad, but Syrian Foreign Minister Walid Muallem repeated the regime's denial on Thursday.
The global chemical weapons watchdog said it has "initiated contact" with Syrian authorities to investigate the attack.
The Organization for the Prohibition of Chemical Weapons (OPCW) said in a statement it also has asked all members of the Chemical Weapons Convention to share "any information they may have regarding the allegations of chemical weapons use in the Khan Sheikhun area of Idlib province" in Syria.
The OPCW said on Thursday that its Technical Secretariat has been "collecting and analysing information" about the April 4 attack as part of its ongoing fact-finding mission which investigates allegations of the use of chemicals as weapons in Syria's civil war.
The secretive organisation has not said if it has staff or investigators on the ground in Syria.
The fact-finding mission gathers information from witnesses and analyses samples gathered from the sites of alleged attacks and from victims.
In the past it has concluded that chlorine and sulfur mustard almost certainly have been used as weapons.