United Nations investigators say fighting in Syria has “escalated dramatically” despite a commitment by both the government and opposition forces to halt violence under international envoy Kofi Annan's peace plan.

In a report Wednesday to the U.N. Human Rights Council, the investigators said the situation in Syria is “dangerously and quickly deteriorating.” The report said there is evidence of human rights abuses committed by both sides, but that violations by Syrian government forces are occurring on an “alarming” scale.

It said that in the case of the May 25 attack on the town of Houla, which killed 108 people, pro-government forces may have been responsible for “many of the deaths.” However it said the role of opposition or foreign forces could not be ruled out and that the investigation will continue.

U.N.-appointed investigator Paulo Pinheiro said his team was particularly concerned about reports of the opposition using children as medical porters and messengers, and exposing them to the risk of death and injury.

Syria criticized the proceedings and said it would not participate in what it called a politicized process.

In violence Wednesday, Syria's state-run news agency said an “armed terrorist group” killed three people during an attack on a pro-government television station. SANA said terrorists planted explosives during the attack at the headquarters of the al-Ikhbaria satellite channel, but did not say how the employees died.

Syria often uses the term “armed terrorists” to label the rebels leading the revolt against President Bashar al-Assad's nearly 12-year rule.

Also Wednesday, Annan's deputy told the Human Rights Council that the mediator intends to hold an international meeting on Syria in Geneva on Saturday. Russia's ambassador to the United Nations said Tuesday that Foreign Minister Sergei Lavrov would attend such a meeting.