Beirut - Syria's state-run media on Wednesday criticised decisions by the US and other nations to expel the country's diplomats, describing the moves as "unprecedented hysteria" and warning they might deal a fatal blow to an international peace plan.
The harsh rhetoric came as Syrian forces bombarded rebel-held areas in the same province where a recent assault killed 108 people, activists said.
Survivors of the Houla massacre blamed pro-regime gunmen for at least some of the carnage as the killings reverberated inside Syria and beyond, further isolating President Bashar al-Assad and embarrassing his few remaining allies.
The Syrian government denied its troops were behind the killings and blamed "armed terrorists".
Damascus had said it would conclude its own investigation into the Houla deaths by Wednesday but it was not clear if the findings would be made public.
The Houla killings prompted Western nations to expel Syrian diplomats in a co-ordinated protest.
Attempt to salvage plan
Japan joined the protest on Wednesday, ordering the Syrian ambassador in Tokyo to leave the country because of concerns about violence against civilians. Japan's foreign minister, Koichiro Genba, said his country was not, however, breaking off diplomatic ties with Syria.
The announcement came a day after the United States, Britain, Canada, Australia, France, Germany, Italy, Spain and Bulgaria ordered top Syrian diplomats to leave.
UN special envoy Kofi Annan met with Assad on Tuesday in Damascus to try to salvage what was left of his peace plan, which since being brokered six weeks ago has failed to stop any of the violence on the ground.
The Al-Baath daily, the mouthpiece of Assad's Baath Party, said Syria won't be intimidated by such "violent rhythms" and would remain standing in front of such "ugly, bloody and dramatic shows". It added that "Syria will not tremble as they think."
The government's Al-Thawra newspaper also blasted the Western decision, calling it an "escalation that aims to besiege Annan's plan and enflame a civil war".
Tensions have escalated as more information emerges about the 25 May killings in Houla.
The UN's human rights office said most of the 108 victims were shot execution-style at close range, with fewer than 20 people cut down by regime shelling.
UN peacekeeping chief Herve Ladsous said there are strong suspicions that pro-Assad fighters were responsible for some of the killings, casting doubt on allegations that "third elements" - or outside forces -were involved, although he did not rule it out.
On Sunday, Foreign Ministry spokesperson Jihad Makdissi said a committee comprising the ministries of justice, defence and interior was set up to investigate the massacre and would have the job done within three days.
Meanwhile, activists said Syrian troops shelled restive suburbs of Damascus and rebel-held areas in the central city of Homs on Wednesday.
The Britain-based Syrian Observatory for Human Rights and the Local Co-ordination Committees said at least five people were killed in the Damascus suburb of Douma.
Both groups had no details about casualties in Homs, which is the provincial capital of the province that includes Houla.