Supporters of Syrian President Bashar al-Assad wave national flags after his speech in Damascus June 20, 2011, in this handout photograph released by Syria"s national news agency SANA.

Activist have accused Syrian security forces of killing seven protesters in the capital Damascus, Idlib province and Deraa on Friday, as they fired live ammunition while hundreds of thousands of demonstrators poured onto the country's streets.

Security agents used live ammunition to disperse protesters in the Qabun and Barzeh areas of the Damascus, while more demonstrators infiltrated the Madaya, Harasta and Saqba regions, said Abdel Karim Rihawi, of the Syrian League for the Defence of Human Rights.

Rihawi added that about 20,000 people had turned out in the Damascus neighbourhood of Qabun, where two people were killed, and three others were killed in Idlib.

Also, in the central city of Homs, 15 people were reportedly wounded by the security forces, pro-democracy militants said.

Friday prayers gave way to new mass demonstrations as protesters demanded the release of hundreds of people detained in earlier demonstrations, after activists issued an appeal for protests to mark a day of "freedom for the hostages" on The Syrian Revolution 2011 page of Facebook, considered to be a driving force behind the demonstrations.

The Facebook appeal called for nationwide demonstrations to protest "for the freedom of prisoners, for the dignity of free men."

In addition to Friday's protests, organisers called for a simultaneous "Conference of National Salvation" to be held on Saturday in Damascus and Istanbul to look at ways to oust President Bashar al-Assad.

A statement said the conference will be held simultaneously in both cities "to draw up a road map that will bring the country out of despotism towards democracy and define the mechanism to overthrow the regime (as) sought by the (people of the) Syrian street."

The official Sana news agency said "armed men fired on security forces and citizens in the areas of Qabun and Rukn Eddin in Damascus.", once again siding with the regime who blames most of the civilians death on armed gangs.

Rami Abdel Rahman of the Syrian Observatory for Human Rights said about 350,000 people turned out in the eastern city of Deir Ezzor, while 150,000 others in Hama protested against President Bashar al-Assad.

Also according to activists, 7,000 people headed towards the Al-Hassan Mosque in the Midan area of Damascus, a focal point of protest in the capital.

As Turkey has seen thousands of Syrians flee to the country after the government crackdown, Turkey's Foreign Minister Ahmet Davutoglu has spoken of the need for Assad to announce "without further delay a calendar of reforms," which would bring an end to the violence in Syria.

In an interview published on Thursday, U.S. Ambassador Robert Ford warned President Assad and his regime that "the street will wash them away" unless they adopt reforms at "the speed demanded by the street protesters."

Tensions between Syria and the U.S. mounted in the last week after Ford visited the city of Hama, where a mass demonstration was taking place.

On Monday pro-Assad supporters retorted by attacking the American embassy in Damascus, which the U.S. said was staged by the Assad regime itself.

Since then various U.S. officials, including Secretary of State Hillary Clinton have reiterated that President Assad has lost legitimacy and should therefore step down from power..

Since the protests began on March 15, violence has killed 1,419 civilians and 352 members of the security forces, while more than 1,300 people have been arrested, according to the Syrian Observatory for Human Rights.