Two Afghans accused of converting to Christianity, including a Red Cross employee, could face the death penalty, a prosecuting lawyer said on Sunday.

Musa Sayed, 45, and Ahmad Shah, 50, are being detained in the Afghan capital awaiting trial, the prosecutor in charge of western Kabul, Din Mohammad Quraishi, told AFP.

"They are accused of conversion to another religion, which is considered a crime under Islamic law. If proved, they face the death penalty or life imprisonment," Quraishi said.

Quraishi said Sayed, who works for the International Committee for the Red Cross (ICRC) had already confessed and there was "proof" against Shah.

The ICRC's spokesman in Kabul, Bijan Frederic Farnoudi, confirmed Sayed's arrest and said the detained man had worked for the organisation since 1995.