BEIRUT — The United Nations’ top human rights official assailed the Syrian government Friday for a campaign of “ruthless repression and killings,” and called for the international community to take steps to prevent the Middle East nation from plunging into civil war.

A statement issued in Geneva by Navi Pillay, U.N. high commissioner for human rights, essentially backed claims by anti-government activists who say Syrian authorities have routinely attacked protesters without provocation. In contrast, the administration of President Bashar Assad has blamed the violence on terrorists armed from abroad seeking to overthrow the government.

Pillay’s comments appeared to be the toughest to date from the U.N., where a resolution condemning Syria’s response to more than six months of protests failed to pass the Security Council this month.

The Assad government faces a hardening of attitudes against it on many fronts. European countries and the U.S. have imposed economic sanctions. Turkey, Syria’s longtime ally, has harshly criticized Assad’s handling of the unrest and is planning to impose economic penalties.

“Since the start of the uprising in Syria, the government has consistently used excessive force to crush peaceful protests,” Pillay said. “Sniping from rooftops and indiscriminate use of force against peaceful protesters – including the use of live ammunition and the shelling of residential neighborhoods – have become routine occurrences in Syrian cities.”

The result has been “a devastatingly remorseless toll of human lives,” said Pillay, a South African judge, who also expressed fears that the conflict was becoming increasingly militarized.

The death toll since March has topped 3,000, Pillay said, and more than 100 people have died in the past 10 days.