Syrian forces bombard rebel towns The Syrian authorities appear to be preparing to conduct a massacre in a town where the opposition is strong, the US state department said on Monday, citing reports from UN monitors and opposition groups. Victoria Nuland, spokeswoman for the state department, said the US felt "deep alarm at reports from inside Syria that the regime may be organising another massacre" in the town of Haffa. Her comments came as Syrian forces bombarded rebel towns and villages across the country on Monday, activists said, as the regime sought to assert itself over an increasingly bold insurgency. The Syrian Observatory for Human Rights, a UK-based monitoring group, said at least 79 people were killed, including 23 members of the security forces, as the military battled rebels in different parts of the country and shelled areas in the central provinces of Homs and Hama, as well as the coastal province of Lattakia. The regime has used helicopters in recent attacks on the Homs town of Rastan and the Haffa area of Lattakia, the observatory said. Haffa is a predominantly Sunni town, according to activists, in a province which - unusually for Syria - contains large numbers of people from the minority Alawite sect, from which the regime's inner circle is drawn "The situation is very bad and getting worse," said one activist in the city of Homs, which was reported to have come under intense bombardment on Monday. The humanitarian situation is terrible ... the number of the wounded is getting higher, and we don't know what to do about this. Ms Nuland warned the Syrian authorities they should remember the lessons of the Bosnian conflict, where leaders who ordered massacres have been tried for war crimes. "The international community can and does learn what units were responsible for crimes against humanity and you will be held responsible for your actions," she said. However, unlike Bosnia, she gave no indication that the US was moving any closer to endorsing military intervention. Kofi Annan, the international envoy to Syria, said he was "gravely concerned" by reports of an escalation in fighting from both sides. A ceasefire brokered by Mr Annan has been nominally in place in Syria since April 12, which about 300 unarmed UN observers have been deployed to monitor. In reality, the ceasefire, as with other aspects of Mr Annan's six-point peace plan, has not been properly implemented. In a statement released on Monday, Mr Annan said he was "particularly worried" about the recent shelling of Homs and the reported use of mortars, helicopters and tanks in Haffa, calling for the UN monitors to be given access to the area. The violence came after a weekend in which activists said some of the heaviest fighting yet took place in the capital amid reports that rebels are becoming better armed and organised. The Local Co-ordination Committees, an on-the-ground activist network, reported clashes in the Damascus district of Barzeh on Monday. Mr Annan has already told the UN that his peace plan is not working but the international community remains divided in coming up with a new response. Russian said on Monday Sergei Lavrov, its foreign minister, would visit Tehran in the coming days to discuss a mooted international conference on Syria, as well as forthcoming talks on Iran's nuclear programme. "Without Iranian participation the opportunity for constructive international influence on the Syrian issue will not be utilised in full measure," the foreign ministry said in a statement. The US, however, which along with other western and some Arab powers wants to see a tougher line taken with Bashar al-Assad, Syria president, has expressed concern that Tehran's alliance with the Syrian regime makes it unsuitable to participate. Hillary Clinton, US secretary of state, said last week that it was "hard to imagine inviting a country that is stage-managing the Assad regime's assault on its people."