Syrian President Bashar al-Assad on Monday said it would be "difficult" to implement a ceasefire in a week, a proposal for a so-called "cessation of hostilities" was put forth by the US and Russia in Munich on Friday.

"They are saying they want a ceasefire in a week. Who is capable of gathering all the conditions and requirements in a week? No one," Assad told lawyers during a televised speech at Syria's Bar Association in Damascus.

"Who will talk to the terrorists? If a terrorist group refuses the ceasefire, who will hold them to account? Practically, talking (about a ceasefire) is difficult," the Syrian president said.

On Friday, US State Secretary John Kerry and Russian Foreign Minister Sergei Lavrov announced an agreement for the "cessation of hostilities" within a week, billed as a "breakthrough" in the conflict.

However, Assad noted on Monday that the ceasefire would not stop both sides of the conflict from using weapons.

"Regarding a ceasefire, a halt to operations, if it happened, it doesn't mean that each party will stop using weapons," said Assad.

"A ceasefire must mean stopping terrorists from strengthening their positions. Moving weapons, equipment, terrorists or strengthening positions must all be forbidden," the Syrian president added.

Since UN-backed talks aimed at bolstering a political solution to the conflict broke down early February, Syrian government forces have gained ground with the help of Russian airstrikes.

UN envoy to Syria Staffan de Mistura, who described the ceasefire to DW as a "breakthrough," arrived in Damascus late Monday to discuss the implementation of the ceasefire and renewing peace talks.

ls/jm (AFP, dpa, AP, Reuters)