Annan demands Syrian government begins ceasefire 'now'
The UN and Arab League envoy to Syria, Kofi Annan, expects the government to implement his peace plan immediately.
Mr Annan's spokesman, Ahmed Fawzi, told reporters: "The deadline is now."
The peace plan, which the government accepted on Tuesday, calls for a UN-supervised cessation of armed violence in all its forms by all parties.
But activists say government forces have been shelling the central city of Homs and fighting armed rebels in the eastern province of Deir al-Zour.
Five people were killed as clashes erupted in the town of Quriya, not far from the border with Iraq, when troops opened fire on a protest, according to the Syrian Observatory for Human Rights.
Earlier, two people were reportedly killed by government snipers in Homs and the city of Idlib, and two others were shot dead as they drove through a rural part of Homs province.
The Local Co-ordination Committees, an activist network, said 37 people had been killed nationwide, including four children and two women.
'Gesture of good faith'
Mr Fawzi said there clearly not been a "cessation of hostilities on the ground" in Syria this week despite the government's acceptance of Mr Annan's peace plan, which has the backing of the UN Security Council.
"This is our great concern," he told a news conference in Geneva. "We expect [President Bashar al-Assad] to implement this plan immediately."
In addition to a ceasefire, it calls for the withdrawal of soldiers and heavy weapons from cities, the release of prisoners, delivery of humanitarian aid to those who need it and free movement for journalists.
Mr Annan wanted the government to implement the ceasefire first, but also rebels to "lay down their arms and start talking", Mr Fawzi added.
"If you read the agreement... it specifically asks the government to withdraw its troops, to cease using heavy weapons in populated centres.
"The very clear implication here is that the government must stop first and then discuss a cessation of hostilities with the other side and with the mediator.
"The rationale is very simple. We are appealing to the stronger party to make a gesture of good faith and stop the killing. We are certain that if that happens, the opposition will follow suit."
He also said Mr Annan planned to visit Tehran and Riyadh to build support for the peace plan, but did not say when.
Meanwhile US Secretary of State Hillary Clinton is in Saudi Arabia for talks on the Syrian crisis.
The US Treasury also announced it was imposing a travel ban and asset freeze on another three senior Syrian officials - Defence Minister Dawoud Rajiha, Deputy Army Chief-of-Staff Munir Adanov and Zuhair Shalish, also known as Dhu al-Himma Shalish, the head of presidential security.
On Thursday, Arab leaders meeting in Baghdad called for Mr Annan's peace plan to be implemented immediately and completely.
"The solution for the crisis is still in the hands of the Syrians as a government and opposition," Arab League Secretary General Nabil al-Arabi told the summit in the Iraqi capital.
Mr Arabi also called on the Security Council to issue a binding resolution to "not only stipulate the necessity of stopping the violence, but also finding a suitable mechanism to cease fire".
President Assad, who was not invited, said he accepted Mr Annan's initiative, but it was "necessary to obtain commitments from other parties to halt the terrorist acts by the armed groups and to withdraw the weapons of these groups and call on them to stop their terrorist acts".
Countries which "support the armed groups with money and weapons must be persuaded to stop this immediately", he added.
Meanwhile, the UK announced an extra £500,000 ($800,000) of support for Syrian opposition groups both inside and outside the country.
Foreign Secretary William Hague said the money would provide "non-lethal" aid to political opponents of President Assad, including to help activists co-ordinate protests and gather evidence of atrocities.
He urged Mr Assad to accept he had no hope of political survival.
The media rights body, Reporters Without Borders, condemned the killing of two journalists who it said were shot dead after an attack by Syrian forces on a group of people trying to enter Syria from Turkey on Monday.
It named the victims as Walid Blidi, a British national of Algerian origin, and Nassim Terreri, whose nationality has yet to be established. A third journalist was wounded in the attack and is in a hospital in Antakya.
The UN says at least 9,000 people have been killed since pro-democracy protests erupted last March. The government says about 3,000 members of the security forces have died combating "armed terrorist gangs".