Syrian President Bashar al-Assad has offered a national dialogue to consider political reforms but continued to blame the country's recent unrest on “saboteurs” and a foreign plot attempting to exploit calls for change.

The 70-minute speech at Damascus University Monday was only his third major address since anti-government protests began in March.

Mr. Assad said the national dialogue – first announced last month – 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 demonstrations 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.

Before Monday's speech, British Foreign Secretary William Hague called on Mr. Assad to either reform or step aside. Hague said he hoped Turkey would pressure neighboring Syria and tell Mr. Assad he is “losing legitimacy.”

In a speech two weeks after the protests began, Mr. Assad said foreigners had created a conspiracy to bring down his government. In mid-April, he said the government would abolish the 50-year-old emergency law and that he was urging his Cabinet to consider measures to create new jobs.

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.