Twenty convicted drug traffickers were hanged Saturday in Iran, officials said.

Those executed had been arrested between 2004 and 2008, the Fars news agency said. Officials said about 700 kilograms (around 1,500 pounds) of cocaine, heroin and opium had been confiscated from them.

The executions took place at a prison in Karaj near Tehran.

An amnesty board rejected appeals from the condemned. Officials said most of them had criminal records at the time of their trafficking arrests.

Human Rights Watch says Iran holds more executions than any country except China, with at least 346 last year. Capital crimes include murder, rape, armed robbery and drug trafficking.