Syrian rebels and the opposition have accused the Lebanese Shia group Hezbollah of attacking Syrian villages.
The Syrian National Council (SNC) said Hezbollah fighters
attacked three villages near the Lebanese border in support of the
Syrian government.
Hezbollah said three Lebanese Shia were killed in the
clashes. Hezbollah has consistently denied it has sent its members to
fight for the Syrian regime.
The UN meanwhile has said human rights abuses in Syria have got worse.
In a report issued on Monday, a UN-appointed inquiry team
said the conflict had become "increasingly sectarian... radicalised and
militarised", according to AFP news agency.
The panel said war crimes by both sides were growing,
although it said abuses by rebels were not on the same scale as those
committed by government forces.
UN human rights investigator Carla del Ponte said it was time
the UN Security Council referred the issue of war crimes to the
International Criminal Court.
Last week, the UN said it estimated 70,000 people had been
killed in the conflict since the uprising against President Bashar
al-Assad began nearly two years ago.
'Unprecedented invasion'
According to the SNC and Syrian Revolution General Commission
(SRGC) opposition groups, Hezbollah fighters crossed into central Syria
on Saturday and attacked three villages in the Qusayr region of Homs.
"The Hezbollah force moved on foot and was supported by
multiple rocket launchers. The Free Syrian Army [FSA] had to call in two
tanks that had been captured from the Assad army to repel the attack,"
SRGC spokesman Hade al-Abdallah told Reuters news agency.
FSA spokesman Luay al-Miqdad called the alleged Hezbollah
operation an "unprecedented invasion", according to a report in the
Lebanese newspaper An Nahar.
"Hezbollah's invasion is the first of its kind in terms of
organisation, planning and coordination with the Syrian regime's air
force," Mr Miqdad was quoted as saying.
An unnamed Hezbollah spokesman was reported as confirming the
three Shia deaths, but without saying whether they belong to the group.
AFP news agency quoted the spokesman as saying the dead fighters had been acting "in self-defence".
At least five Syrian rebels were also killed in the clashes, unconfirmed reports said.
Hezbollah is one of the biggest groups in Lebanon's governing
coalition and is strongly backed by Iran, a close ally of President
Assad. Mr Assad's minority Alawite sect is an off-shoot of Shia Islam.
Besides the Lebanese army, Hezbollah's armed wing is by far the strongest and best equipped in the country.
Lebanese officials have long accused Hezbollah's military
wing, the Islamic Resistance, of fighting in Syria, while the US says
Hezbollah provides training, advice, and logistical support to the
Syrian military.
The latest reports come days after a senior commander of
Iran's Revolutionary Guards was killed travelling from Syria to Lebanon.
BBC