With hundreds dead from a suspected chemical weapons attack in eastern Damascus, US President Barack Obama said reports the Syrian government was responsible for the deadly attacks on its own people were “a big event of grave concern”. Syrian opposition groups said as many as 1300 people died on Wednesday in a chemical weapons attack on the suburb of Ghouta, a toll that could not be independently verified. A chemical attack, if confirmed, would be the worst atrocity in 2½ years of civil war in which more than 100,000 Syrians have died and millions more have been displaced, according to UN estimates. Mr Rudd was due to fly to Brisbane for pre-arranged private meetings, before flying to Canberra on Saturday evening for briefings with other ministers on the unfolding situation in Syria and to consider Australia's response in the event of international action. Mr Rudd revealed he spoke with UN secretary-general Ban Ki-Moon about the matter on Friday.

But he would not be drawn on whether Australia would participate in a military response if it were authorised by the UN Security Council or the United States. He said the first priority was to establish the facts in consultation with Australia's foreign allies and the international community, and then to offer “a calm, sober response”. “When you are talking about the use of weapons of mass destruction, against large civilian concentrations, this is a matter of concern for all decent human beings.” Opposition Leader Tony Abbott will continue his campaign but will receive a briefing on the Syria crisis from senior officials on Sunday afternoon in Brisbane. During a press conference in Adelaide, Mr Abbott initially said that his foreign affairs spokeswoman Julie Bishop would be briefed on Sunday and that he would in turn be briefed by Ms Bishop.

He added: “And obviously I’m happy to receive briefings as well as this situation unfolds.” But after the press conference, Mr Abbott’s spokesman said the Opposition Leader would now himself attend the briefing from officials including Foreign Affairs head Peter Varghese in Brisbane on Sunday afternoon, after the Liberal Party campaign launch. Mr Abbott said it was “entirely appropriate for the Prime Minister to receive briefings on Syria”. “Obviously terrible things are happening in that country. It’s very important that United Nations inspectors be allowed in to get to the bottom of exactly what has happened. I hope the international community is able to do what it can to try to ensure that the bloodshed ceases and ordinary human rights are once more respected.” Asked why he didn’t feel it necessary to travel to Canberra for an immediate briefing, Mr Abbott said: “I don’t for a second underplay the seriousness of the situation and I entirely support the Prime Minister receiving briefings … Certainly I will be continuing my campaign but in between ordinary campaign events I will be receiving briefings and updates on the situation in Syria.”

Mr Abbott said it was too early to determine what kind of additional assistance Australia might offer, either in financial aid or an increased refugee intake. “I accept that it is a very serious situation in Syria. It is an escalating situation, it seems. Australia will do what it can to help. We have always been a good international citizen. We will do our duty as far as we humanly can but I think it’s too early to speculate on exactly what that might be.” Loading Earlier on Saturday, an exclusive Fairfax-Neilson poll showed Labor's primary vote had slipped to 35 per cent, against the Coalition's 47 per cent. Mr Rudd's seat of Griffith was also under dire threat from LNP candidate Bill Glasson, who led 52-48. With David Wroe