Iran has hanged 22 people convicted of drug trafficking, a state-owned newspaper has reported.

The hangings happened on Sunday at two prisons, Evin in Tehran and Rajai Shahr, just outside the capital, IRAN daily said on Monday.

"Subsequent to the trials of 22 big-time traffickers, the Islamic Revolutionary Court found them guilty based on the existing evidence and handed down execution sentences," it said.

The hangings are the latest mass executions by a state that, according to rights groups, has the highest per capita death penalty rate in the world. 

Amnesty International says Iran is second only to China for the total number of executions carried out.

Tehran dismisses criticism of its justice system, saying it is implementing Islamic law and responding to a major drugs problem.

Iran is a transit route for narcotics smuggled from neighbouring Afghanistan, which produces more than 90 per cent of the world's supply of opium.

More than 3,500 Iranian security personnel have been killed fighting drug smugglers since Iran's 1979 Islamic revolution.

Murder, adultery, rape, armed robbery, drug trafficking and apostasy, the renouncing of Islam, are all punishable by death under Iran's Islamic law, practised since the revolution.

Source: Agencies