The Turkish government said Thursday that the number of Syrians who have crossed into Turkey amid fears of government retaliation has risen to at least 1,600.

The refugees are looking to escape Syrian President Bashar al-Assad's weeks-long crackdown against anti-government protesters. Some say that black-clad gunmen have opened fire against protesters without warning.

The Syrian government accused 'armed gangs' in the border region of 'massacring' 120 security force members in recent days and vowed to take decisive action. There were media reports of Syrian forces moving to fortify positions in the north on Thursday.

The refugee flow comes amid behind-the-scenes diplomatic efforts in the United Nations to stem the violence.

Russia announced Thursday that it opposes a United Nations Security Council resolution condemning Syria for its crackdown on anti-government protesters.

Foreign Ministry spokesman Alexander Lukashevick says Syria's unrest does not pose a threat to world peace or security.

Lukashevick commented a day after European members of the Security Council presented a revised draft measure to the council.

The measure calls for an immediate end to the violence in Syria and humanitarian access to into Syria. It also urged Syria's government to enact genuine political reforms.

Separately, the U.N.'s top human rights official has accused Syria of trying to “bludgeon its population into submission” with its crackdown on anti-government protesters.

The U.N. High Commissioner for Human Rights, Navi Pillay, said Thursday that it is “utterly deplorable” for any government to deploy tanks, artillery and snipers against its people. She urged Syria to “halt this assault” against Syrians' “most fundamental human rights.”

Rights groups say at least 1,100 people have been killed in the Syrian crackdown against the anti-government campaign that began in March. More than 10,000 people have been arrested.