A ceasefire has come into force in Syria amid doubts expressed by Western countries about the government’s willingness to stick to it.
Correspondents say the truce appears to be largely holding, with no reports of casualties or deaths so far.
However there were some reports of shelling and firing in the early hours.
The Syrian government and the armed opposition have both said they will abide by the ceasefire, but reserved the right to respond if attacked
Syrian foreign ministry spokesman Jihad Makdissi said the government was “fully committed” to the cessation of all military operations “as long as we have no armed violence against the state”.
“If those people at the external opposition want the full benefit of their own country, they have to come to the table of negotiation and table of dialogue.”
The ministry had also written to UN-Arab League envoy Kofi Annan – who brokered the plan – pledging to observe the truce while reserving the right to “respond proportionately” to rebel attacks.
Col Kassem Saadeddine, of the main armed rebel group, the Free Syrian Army (FSA), said that if the regime “does not stop shelling and not withdraw tanks, we will intensify our military operations and launch attacks.
The BBC’s correspondent in Beirut, Jim Muir, says there were some reports of shooting and shellfire early on Thursday in cities including Idlib and suburbs of the capital, Damascus, but that the truce appeared to be largely holding.
If it continues, the focus is expected to fall on the withdrawal of government troops, tanks and heavy weaponry, says our correspondent. That step was supposed to have been completed on Tuesday.
However, there is a long way to go before the situation can be considered stable, he adds.
The main political opposition group, the exiled Syrian National Council (SNC), said a new wave of protests against President Bashar al-Assad would begin as soon as a ceasefire began, which would test the government’s pledges.
“We call on the people to demonstrate and express themselves,” SNC leader Burhan Ghalioun told AFP news agency in Beirut.
“The right to demonstrate is a principle point of the plan,” he said.
Mr Annan is due to brief the UN Security Council later on Thursday.
British Foreign Secretary William Hague said the UK was ready to work at the UN to send monitors to Syria once a ceasefire was in place, “to make sure they can’t slide back to renewed conflict”.
But if the ceasefire collapsed, the UK “will want to return to Security Council in a new attempt to obtain a resolution on Syria, we’ll intensify our support for the opposition and we will seek stronger sanctions”.
Following a phone call between German Chancellor Angela Merkel and US President Barack Obama, the two leaders said they “shared the concern that the Assad government was not complying with the terms of the agreement negotiated by Kofi Annan”.
Some influential voices in the US Congress have been calling for the Syrian opposition to be armed.
The violence had continued on Wednesday, with activists reporting at least 30 people killed in offensives around the country.
The UN estimates about 9,000 people have died since anti-government protests began in March 2011. In February, the Syrian government put the death toll at 3,838 – 2,493 civilians and 1,345 security forces personnel.