Tens of thousands of Syrians have gathered for rallies backing President Bashar al-Assad, a day after the leader blamed the country's recent unrest on “saboteurs” and laid out plans to consider political reforms.

Thousands of demonstrators holding flags and pictures of Mr. Assad gathered Tuesday in the capital, Damascus, while state television showed similar rallies in other cities.

Also Tuesday, the state news service said Mr. Assad has granted a general amnesty for crimes committed before June 20, but did not provide further details.

The measure follows the president's 70-minute speech Monday in which he offered a national dialogue that would begin to review new laws on parliamentary elections, the media and possible reforms to Syria's constitution.

Activists immediately dismissed his promises, saying they failed to engage the demands of protesters who for three months have rallied for democratic changes and defied a fierce military crackdown.

Witnesses and rights groups said widespread protests erupted after Mr. Assad's address, including in the flashpoint province of Idlib, the central cities of Homs and Hama and the suburbs of the capital, Damascus. Protesters condemned the speech and many chanted “Liar! Liar!” as they marched, demanding the Syrian leader's ouster.

President Abdullah Gul of Turkey, a longtime ally, said Mr. Assad's words were “not enough,” adding that he should transform Syria into a multiparty system.

U.S. President Barack Obama spoke by telephone Monday with Turkish Prime Minister Recep Tayyip Erdogan about the situation in Syria. The White House said the two leaders agreed Damascus must end the use of violence and “promptly enact meaningful reforms that respect the democratic aspirations of the Syrian people.”

The U.S. State Department said Washington demands “actions, not words” from the Syrian leader.

Mr. Assad told the nation he is forming a committee to study reforms to Syria's constitution, including one that could empower organizations other than the ruling Ba'ath party. He also warned the “most dangerous” issue facing the country is the “weakness or collapse” of its economy.

The French news agency spoke with refugees at the Turkish border who reacted angrily to the speech.

Turkey is sheltering more than 10,000 Syrian refugees in tent cities near the Syrian border. Turkish officials say another 10,000 are sheltering inside close to the frontier just inside Syria.

Rights activists say more than 1,400 civilians have been killed and 10,000 detained since mid-March in the government's crackdown on protests.