Story highlights The United States says it won't send any observers

The opposition blames the government for the violence

The Syrian government blames "armed terrorist groups" for cease-fire violations

U.N. chief Ban Ki-moon says he is alarmed at continuing violence

A suicide bombing in a Damascus neighborhood killed nine people Friday -- most of them government forces -- and further unraveled an already tenuous ceasefire, Syrian state media reported.

The attack, in the district of Midan, was described by the state-run news agency as a "terrorist bombing."

The opposition Syrian Observatory for Human Rights put the death toll from the suicide bombing at 10, and reported that most of the victims were regime forces.

ITN Reporter Bill Neely arrived at the scene moments after the blast erupted under a highway overpass. Dozens of riot police and troops had been huddled there, prepared to confront any demonstrators as they emerged from a nearby mosque to protest against the government. Such demonstrations are common after Friday prayers.

Neely, who is one of the few Western journalists allowed by the government to report from Syria, said one young man walked up to the security forces; when he was asked for his identification, the man reached into his jacket and detonated a suicide vest.

Body parts and tattered pieces of uniforms strewn nearby testified to the power of the blast, which wounded more than 20 people, many of them seriously, he said.

JUST WATCHED U.N. response in Syria mocked Replay More Videos ... MUST WATCH U.N. response in Syria mocked 02:25

JUST WATCHED Annan's Syria peace plan may be dead Replay More Videos ... MUST WATCH Annan's Syria peace plan may be dead 01:54

JUST WATCHED Opposition: Syria attack kills dozens Replay More Videos ... MUST WATCH Opposition: Syria attack kills dozens 01:12

JUST WATCHED Report: Syrian killings after U.N. visit Replay More Videos ... MUST WATCH Report: Syrian killings after U.N. visit 02:50

JUST WATCHED Syria's deadly lies to U.N. monitors Replay More Videos ... MUST WATCH Syria's deadly lies to U.N. monitors 03:06

JUST WATCHED Shelling of Syrian city intensifies Replay More Videos ... MUST WATCH Shelling of Syrian city intensifies 03:52

Many of the security forces who witnessed the event appeared shell-shocked, Neely said. Damascus has been largely spared such attacks, and the repercussions appeared psychological as well as physical.

The attack represented yet another serious blow to a peace process that has been fragile at best since it began, and evidence that it is being undermined by both sides.

Activists have accused the United Nations of failing to move quickly to get its peace monitors into Syria. As of Friday, just 13 were in the country of 22 million people. Another 15 are scheduled to arrive this weekend. "Are they arriving by horse?" one incredulous activist asked Neely, predicting there would be no peace to monitor by the time all 300 slated to arrive in the coming month actually get there.

Another three members of security forces were killed "when their car was targeted by unknown armed men" in Aleppo, the observatory said.

In addition to that tally, 18 more people -- including a woman and three children -- were killed Friday, according to the opposition Local Coordination Committees of Syria.

The attacks provoked concern from Catherine Ashton, the high representative of the European Union for foreign affairs and security. "I call on all parties in Syria to cease immediately all forms of violence," she said in a statement that reiterated her call for Syrian authorities "to fully respect the terms of the agreement with the UN."

The United States said Friday it does not intend to provide monitors. "We are obviously supporting this mission financially and we are prepared to support it logistically as we evaluate its needs," U.S. State Department spokeswoman Victoria Nuland told reporters.

Syrian government officials and the opposition, meanwhile, traded accusations over the escalating number of cease-fire violations.

Syria consistently blames "armed terrorist groups" for the violence that has wracked the country for 13 months.

Armed terrorist groups have violated the cease-fire more than 1,300 times since it came into effect, Information Minister Adnan Mahmoud told state-run Syrian Arab News Agency.

The government accusations came as an opposition group said it has documented hundreds of deaths since the first United Nations peace plan monitors arrived on April 16.

At least 462 people -- 34 of them children -- have been killed since then, the opposition Local Coordination Committees of Syria said Thursday.

"Violent gunfire and bombing on Syrian cities haven't stopped," the opposition group said.

The international community said Syria has not withdrawn its troops and heavy weapons from population centers as the government agreed to do.

The plan includes calls for President Bashar al-Assad's government and the opposition to end the bloodshed, allow humanitarian groups access to the population, release detainees and start a political dialogue.

U.N.-Arab League joint special envoy Kofi Annan has said that the Syrian foreign minister told him heavy weapons and troops had been withdrawn from population centers and military operations had ended as called for by Annan's six-point peace plan with which Damascus has said it will comply.

But shelling and fighting continues, with at least 35 killed Thursday, many of those deaths in Deir Ezzor, the LCC said.

"This is among the deadliest attacks, and is further proof that the Assad regime has no intention of implementing the Annan plan," said Rafif Jouejati, a spokeswoman for the committees.

Violence has raged between al-Assad's forces and the opposition for more than a year. The United Nations estimates at least 9,000 people have died in the conflict, while activist groups put the death toll at more than 11,000.

CNN cannot independently verify reports of violence and deaths within Syria, as the government has restricted access by most of the international media.