ISTANBUL – The Syrian ambassador to Iraq has defected, denouncing President Bashar Assad in a TV statement Wednesday, becoming the most senior diplomat to abandon the regime during a bloody 16-month uprising.

Nawaf Fares, a former provincial governor, is the second prominent Syrian to break with the regime in less than a week. Brig. Gen. Manaf Tlass, an Assad confidant and son of a former defense minister, fled Syria last week, buoying Western powers and anti-regime activists, who expressed hope that other high-ranking defections would follow.

The high-level defections could be a sign that Assad’s tightly wrapped regime is unraveling, but it was too early to be certain. There have been thousands of defections in the past, mostly low-level army conscripts, but until now no one as senior as the general and the ambassador had fled.

In a statement broadcast on the Arabic satellite channel Al-Jazeera, Fares said he was resigning and joining the opposition. Wearing a dark suit and reading from a prepared text in what appeared to be a large office, Fares harshly criticized Assad.

“I’m announcing from this moment on that I’m siding with the revolution in Syria,” he said, according to the Al-Jazeera translation into English. He called on all Syrians to abandon Assad.

“Where is the honor in killing your countrymen? Where is the national allegiance? The nation is all the people, not one person in particular,” he said. “The allegiance is to the people, not to a dictator who kills his people.”

It was not known where or when Fares recorded the statement.

Appointed to the Baghdad post four years ago, Fares was the first Syrian ambassador to Iraq in 26 years. Like Tlass, he is a member of the privileged Sunni elite in a regime dominated by Assad’s minority Alawite sect.

Khaled Khoja, a member of the opposition Syrian National Council who is based in Istanbul, said Fares was “moving toward Turkey.” Asked for details, Khoja said the information came from his own sources on the ground in Iraq.