An image grab taken from Syrian state television shows Syrian President Bashar al-Assad addressing the nation from Damascus University in the Syrian capital on June 20, 2011. (AFP/GETTY IMAGES)

Even as Syrian President Bashar al-Assad offered new concessions in a televised speech Monday, he remained defiant, blaming the mass protests rocking his government on “saboteurs” and “vandalism.”

Assad, wrestling with the boldest challenge yet to his family’s 40-year-old rule, spoke for more than an hour at Damascus University. But his bid to subdue unrelenting protests and maintain his grip on power by promising reforms failed to mollify his opponents.

Residents who fled their homes in northern Syria to escape the government’s violent crackdown reacted with derision. On the Turkish side of the border, crowds of refugees chanted slogans against Assad, calling him a “liar” and demanding his ouster. On the Syrian side, displaced people reached by phone said that they siphoned electricity from a nearby village to power up a television set in time for his address and that they were dissatisfied by what they heard.

Before an auditorium of supporters, Assad announced intended economic and political reforms, including the formation of a 100-member “national dialogue authority” that would map out a path to those changes. But he said that without stability, there could be no real transformation.

“We can say that national dialogue is the slogan of the next stage,” Assad said. “The national dialogue could lead to amendments of the constitution or to a new constitution.”

Protesters, refugees and observers largely dismissed his concessions as empty promises amid a security crackdown that has left 1,250 people dead. Analysts said his speech made clear that the government felt threatened and was desperate to end the revolt.

Assad “is clearly concerned. They don’t do things unless they have to,” said Andrew Tabler, a Syria expert at the Washington Institute for Near East Policy. “On the other hand, they still haven’t changed the playbook. They still believe that by pretending there isn’t a problem and blaming it on [Islamists], outlaws and others, that people will buy that.”

In a reference to thousands of people flowing across the border into Turkey, Assad urged the “displaced” to return to their homes and said security forces would protect and not attack them. He was careful not to use the term refugees.

The Syrian military moved closer to the border last week, surrounding the frontier town of Bdama, in an apparent effort to stop the continued flow of refugees into Turkey.

Assad said he wanted Syria to stabilize so the troops could return to their barracks and promised to prosecute all those involved in bloodshed. He did not acknowledge that his soldiers were involved in shooting hundreds of unarmed protesters.

“What is happening today has nothing to do with reform, it has to do with vandalism,” he said. “This is a black period in Syria, and we should not continue in a black period.”

It was Assad’s third major address since the pro-democracy demonstrations, similar to those that have been reshaping other Arab countries, began in Syria, triggering violent crackdowns and retaliation from government forces.

Assad spoke to parliament about the crisis March 30, laughing it off, then addressed the government’s newly appointed cabinet April 16. He had not been seen in public since mid-May, however, and last week he refused to take phone calls from U.N. Secretary General Ban Ki- moon.

Although Assad gave no specifics Monday, he promised several reforms, including asking the Justice Ministry to consider widening an amnesty for political prisoners. He said he was open to drafting a new constitution and pledged to reform the political process and organize elections in August, then subsequently have a “national dialogue.”

In response to the speech, U.S. State Department spokeswoman Victoria Nuland said that Assad “has been making promises to his people for years, for weeks. What’s important now is action, not words. . . . We would also note in the speech he spends a lot of time blaming foreign instigators rather than appreciating that his own people are simply disgusted by the regime — by a regime that supports itself through repression, corruption and fear.”

Syria’s political opposition vowed to continue their protests until Assad and his family relinquish power.

The Local Coordinating Committee, an organization of the Syrian opposition, issued a statement calling the speech a “consecration of the crisis by the regime” entrenched “behind denial.” The statement said the speech was a blatant attempt to “buy time” and showed a flagrant disregard for the bloodshed of protesters.

“It seems the main effect of the speech is a psychological one: to reassure his supporters that the president still stands,” said a diplomat in Damascus, who spoke on the condition of anonymity because of the sensitivity of the issue. “It might appease some segments of the opposition and encourage those who advocate dialogue with the regime.”

Nearly 11,000 refugees have fled to Turkey to escape the violence, and an estimated 5,000 displaced people are in the mountains on the Syrian side of the border.

Jamil Saeb, a refugee on the Syrian side, called the speech “empty words.” “We lost our trust in this government and in this leader,” he said. “It’s not a government. It’s a mafia.”

Assad’s call for the displaced to return was met with defiance.

“Tell the army to leave, and then we’ll go back,” said Mohammed Husnawi, a 26-year-old Syrian refugee in Turkey. “No one trusts a word Assad says, and he knows that.”

Cellphone videos posted from towns across Syria showed demonstrators in the streets chanting “Oh, Bashar, you liar” and “Freedom.” In an apparent bid to stave off government accusations that many of the videos are fabricated, some protesters carried signs bearing the date and place of the rally, while in other videos, men announced the time, date and place of the protest. Journalists have generally not been allowed inside Syria to cover the uprising.

Assad assumed power in 2000, after his father’s death, and many thought he could modernize Syria and bring it out from under autocratic rule. But the anticipated reforms never materialized.

On the world stage, Assad is growing increasingly isolated. His most reliable regional ally, Turkey, is critical of the violent crackdowns as refugees continue to flow across the border. And international calls for Assad to reform or step down are growing.

Inside the auditorium at Damascus University, however, such criticism seemed far away. At the close of Assad’s speech, the crowd chanted: “God, Syria, Bashar, and that’s it.”

A Washington Post special correspondent in Damascus and special correspondent Sulafeh Munzir Al Shami in Cairo contributed to this report.