Syrian President Bashar al-Assad said on Monday any ceasefire did not mean each side had to stop using weapons, and nobody was capable of securing the conditions for one within a week.
"Regarding a ceasefire, a halt to operations, if it happened, it doesn't mean that each party will stop using weapons," Assad said in Damascus in televised comments.
"A ceasefire means in the first place halting the terrorists from strengthening their positions. Movement of weapons, equipment or terrorists, or fortification of positions, will not be allowed," he said.
World powers agreed in Munich on Friday to a "cessation of hostilities", scheduled to start a week later, but Syrian army offensives across the country, backed by Russian air strikes, continue unabated.