Bashar al-Assad, Syria's president, has ordered a new general amnesty for all crimes committed in the country up until June 20, in another apparent attempt to calm months of protests against his rule.

The state news agency, SANA, announced the move on Tuesday, nearly a month after Assad issued a similar amnesty for all political crimes.

"President Assad has issued a decree granting a general amnesty for crimes committed before the date of June 20, 2011," SANA reported, without giving details.

The president ordered a reprieve on May 31 for all political prisoners in the country, including members of the outlawed Muslim Brotherhood. Hundreds of detainees were released, according to rights groups.

But the amnesty decrees are believed to be a part of the overtures by the Syrian government to its opposition, largely seen as symbolic. Rights groups have criticised the amnesty measures, calling them insufficient.