The US has expressed fears that the Syrian government "may be
organising another massacre" in the town of Haffa in Latakia province,
where UN military observers have been denied access.
UN Secretary General Ban Ki-moon said it was vital that the observers
should be allowed into the town.
He and peace envoy Kofi Annan expressed grave concern about violence there.
A BBC correspondent travelling with UN observers witnessed sustained
and heavy shelling in the old city of Homs.
The UN observers are in Syria to monitor the implementation of a
putative ceasefire, brokered by Mr Annan, which has all but collapsed.
'Civilians trapped'
Annan's six-point plan
1. Syrian-led political process to address the aspirations and
concerns ofthe Syrian people
2. End to violence by all sides; army troops to stop using heavy
weapons and withdraw to barracks
3. Parties to allow humanitarian aid
4. Authorities to free political detainees
5. Authorities to ensure freedom of movement for journalists
6. Authorities to allow peaceful demonstrations
"The UN made a particular appeal to be able to get into Haffa because
it had heard concerning reports about regime plans," US state
department spokeswoman Victoria Nuland told a news briefing in
Washington.
"At the same time, if you follow Syrian media, they were claiming that
the opposition would cause a massacre."
Earlier this month, activists said Syrian government forces killed 108
people in the region of Houla, in Homs province, and 78 people in the
village of Qubair, in Hama province.
But Ms Nuland downplayedthe idea of foreign intervention in Syria,
saying the emphasis wouldremain on using political and economic
measures to pressure the government of President Bashar al-Assad.
The Syrian government blames the violence on foreign-backed armed
terrorist gangs.
In a statement, Mr Annan, joint envoy for the UN and Arab League, said
there were "indications that a large number of civilians are trapped"
in Homs and Haffa.
Later Mr Ban spoke of the"great danger" to civilians under fire.
"The secretary general underlines the importance of unimpeded access
by UNSMIS to Haffa, amid reports of a build-up of government forces
around the town," he said in a statement.
Syrian government helicopter gunships strafedrebel positions in Haffa,
UN observers and human rights activists said.
The BBC's Paul Danahar: "I was watching a mortar land pretty much every minute"
Heavy fighting was also reported in Rastan and Talbisa, north of Homs
city,"with artillery and mortar shelling, as well as firing from
helicopters, machine guns and smaller arms", said a statement from the
UN Supervision Mission in Syria (Unsmis).
A car bomb exploded in thecity of Deir al-Zour, killing 10 people, the
London-based Syrian Observatory for Human Rights said, quoting sources
on the ground.
Fighting was also reported in Idlib province.
It is impossible to confirm these reports independently, as Syria
heavily restricts journalists'freedom of movement.
Russia, which supports the Syrian government, called for Iran to take
a role in ending the 15-month old conflict.
Last week, US Secretary of State Hillary Clinton rejected the idea of
involving Iran, which she accused of "helping to stage-manage the
repression" in Syria.
Russian Foreign Minister Sergei Lavrov will travel to Tehran on
Wednesday to discuss the initiative, the foreign ministry said.