BEIRUT - UN observers have discovered 13 bound corpses in eastern Syria, many of them apparently shot execution-style, the monitoring mission says.
The announcement comes days after a massacre in Houla, in the central Homs province, which killed more than 100 people and prompted worldwide condemnation against the regime of President Bashar Assad.
The Syrian government denied its troops were behind the killings and blamed armed terrorists.
The latest killings apparently happened in Deir el-Zour province.
The corpses were found with their hands tied behind their backs, according to a statement by the UN mission.
Some appeared to have been shot in the head from a short distance.
The head of the UN observer team, Major General Robert Mood, said he was deeply disturbed by this appalling and inexcusable act.
The violence in Syria is spiralling out of control as an uprising against Assad that began in March 2011 has morphed into an armed insurgency.
In the wake of the Houla massacre, the US and several other countries expelled Syrian diplomats to protest the killings.
Survivors blamed pro-regime gunmen for at least some of the carnage in Houla. The UNs top human rights body planned to hold a special session on Friday to address the massacre.
The US Treasury Department said it was levying sanctions on a key Syrian bank as it seeks to ratchet up economic pressure on the regime.
The department said the Syria International Islamic Bank has been acting as a front for other Syrian financial institutions seeking to circumvent sanctions.
The new penalties will prohibit the SIIB from engaging in transactions in the US and will freeze any assets under US jurisdiction.
Violence also continued elsewhere unabated. Syrian forces bombarded rebel-held areas in the same province where the Houla killings occurred.