BEIRUT — Syria “absolutely rejects” any plans to send Arab troops into the country, the Foreign Ministry said Tuesday, even as the death toll mounts from 10 months of violent conflict.

Thousands of people have been killed in the regime’s crackdown on the anti-Assad revolt, which has turned increasingly militarized in recent months with a growing risk of civil war. The U.N. says about 400 people have been killed in the last three weeks, on top of an earlier estimate of more than 5,000 killed since March.

The leader of Qatar, Sheik Hamad bin Khalifa Al Thani, was quoted Sunday as saying Arab troops should be sent to Syria to stop the deadly violence — the first statements by an Arab leader calling for the deployment of troops inside Syria.

Qatar, which once had close relations with Damascus, has been a harsh critic of President Bashar Assad’s crackdown. The wealthy Gulf state withdrew its ambassador to Syria in the summer to protest the killings. Since the Arab Spring began more than a year ago, Qatar has taken an aggressive role, raising its influence in the region.

The government says terrorists are behind the uprising — not reform-seekers — and that armed gangs are acting out a foreign conspiracy to destabilize the country.

Syria’s powerful ally Russia said Wednesday it would block any attempt by the West to secure U.N. support for the use of force against the regime in Damascus, Foreign Minister Sergey Lavrov said Russia’s draft of a U.N. Security Council resolution on the violence in Syria that circulated Monday was aimed at making it explicitly clear that nothing could justify a foreign military interference.

The Security Council has been unable to agree on a resolution since the violence began in March because a strong opposition from Russia and China. In October, they vetoed a West European draft resolution, backed by the U.S., that condemned Assad’s attacks and threatened sanctions.

Lavrov said Russia would reject any attempts at securing a U.N. sanction for a military interference in Syrian affairs.

“If some intend to use force at all cost … we can hardly prevent that from happening,” he said. “But let them do it at their own initiative on their own conscience, they won’t get any authorization from the U.N. Security Council.”

A recent visit by the commander of Iran’s elite Quds force to Damascus is the strongest sign yet that Iran is supplying weapons to aid Bashar Assad’s crackdown on the Syrian people, a senior Obama administration official said Tuesday.

While the U.S. has long believed Iran is helping drive the deadly crackdown on dissent in Syria, the official says the visit by Quds Force Commander Ghassem Soleimani provides a concrete example of direct high-level cooperation between Iran and Syria.

The administration’s assertion comes amid heightened tensions between Washington and Tehran. Under the threat of increased U.S. sanctions, Iran has said it could block the strategic Strait of Hormuz; the Obama administration says it has warned Iran against taking such actions.

Iran has been Syria’s closest ally for decades, and the Islamic Republic has been a vocal supporter of Assad since the uprising against his regime began in March.