BEIRUT — Syria’s government on Monday announced details of a new law permitting the formation of opposition parties for the first time in 48 years, but the terms were so restrictive the move seems unlikely to defuse the four-month-old uprising against the rule of President Bashar al-Assad.

According to the official news agency SANA, the law requires parties to be vetted by a government committee and to pledge allegiance to the constitution, which, in its current form, guarantees the supremacy of the ruling Baath Party.