Five Kurdish asylum seekers in Australian immigration detention centres are on a hunger strike to protest being detained for more than two years.

Australian media report that three of them have sewn their lips together, and two have been transferred to hospital.

Australian authorities have rejected their applications for residency, but the five prisoners have not been deported because they do not hold Iranian or Iraqi citizenship. They belong to a minority Shiite Kurdish group that settled around the Iran-Iraq border. In 1970, Saddam Hussein, then the president of Iraq, exiled many of them to Iran and withdrew their Iraqi citizenship.

A spokesman for Australian immigration said the hunger strikers are receiving medical care and they have been told that their actions will not alter the outcome of their cases.