The United States expects the Syrian government to respect the right of citizens to demonstrate peacefully, President Barack Obama's deputy national security adviser said on Monday.

Denis McDonough's remarks came after Syrian security forces opened fire on hundreds of demonstrators chanting against emergency laws in the southern city of Daraa on Monday.

Open gallery view Anti-Syrian government protesters flash V sign as they protest in the southern city of Daraa, Syria, Wednesday March 23, 2011. Credit: AP

Syria has been rocked by more than a week of demonstrations that began in Daraa nearly two weeks ago and exploded nationwide last Friday.

In a move to quell the unrest, Syrian Vice President Farouq al-Shara said Monday that President Bashar Assad planned to announce important decisions that would "please the Syrian people" in the next two days.

Shara was speaking to Lebanese Hezbollah's al-Manar television, which gave no give further details on the matter. Assad has been facing the biggest challenge to his 11-year rule after two weeks of anti-government protests spread across the country.

Assad pledged several reforms after the unrest began in the country, but his efforts failed to appease protesters who are enraged after a violent crackdown on demonstrations in several cities.

At least 55 people are believed to have been killed in and around Daraa alone, as secret police and special forces try to quell the protests.

Earlier in the day, Turkish Prime Minister Recep Tayyip Erdogan said that he had spoken to Assad twice in the past three days and advised the Syrian leader to answer the people's calls with a reformist, positive approach.

Syria is working on reforms, including lifting emergency rule and restrictions on political parties, Erdogan said.

But activists continue to call for protests ahead of Assad's expected speech.

"We call for daily demonstrations and will not announce a place for protesters to gather because police will turn these areas into military zones," activists said on the Facebook page The Syrian Revolution 2011.

On Sunday, the Interior Ministry urged Syrians on Sunday not to respond to calls to protest near Damascus' Umayyad Square.

"These messages you are receiving on your phones are the work of the people who want to incite strife in Syria," state television said.

Assad has convened the leadership of his Baath Party to consider the steps to take to quell the unrest. Hezbollah's Al-Manar television in Lebanon reported that a shake-up of the Syrian cabinet was one of the moves being debated, along with the release of political prisoners.

Bashar Assad has been president since 2000, taking over after the death of his father, Hafez al-Assad.