Hundreds of Syrians have been released from government prisons after an amnesty granted by President Bashar Assad to mark his re-election this week, a monitoring group said Friday.

The Syrian Observatory for Human Rights said 320 prisoners were from northern Aleppo Central prison on Wednesday as Assad's victory in presidential elections was announced.

The Britain-based group said 480 other prisoners, including 80 women, would be freed from Adra prison in Damascus province.

Several dozen were freed Friday from Adra, while the rest of the 480 slated to walk free were transferred to a municipal building pending their release, the monitoring group said.

The Observatory said that all the Adra prisoners to be released had been held on charges of "terrorism," a term the government uses for those involved in the uprising.

An estimated 18,000 people are being held in Syria's prisons.

Around 3,500 detainees are believed to be held at Aleppo's Central prison, which rebels have repeatedly attacked since April 2013.

Last month, Syrian troops ended a year-long rebel siege of the prison, with tanks and armored vehicles rolling into the grounds of the sprawling facility.

Conditions inside the prison are reportedly dire, and the Observatory says 600 prisoners have died there because of lack of food and medicine as well as bombardment.

Observatory director Rami Abdel Rahman, citing lawyers for detainees, told Agence France Presse that the prisoner releases were reportedly a post-election "gesture" by Assad.

He won a new seven-year term with nearly 90 percent of votes cast in Tuesday's election, which the opposition and much of the international community have slammed as a "farce."

Assad faced two little known candidates in the election.