Four members of the SOS Chretiens d'Orient (Christians of the Middle East) charity went missing near the French embassy in the Iraqi capital Baghdad, the organisation's director Benjamin Blanchard told a press conference in Paris.

No ransom demand has been received as yet and no group has claimed responsibility for their disappearance, he added.

SOS Chretiens d'Orient has been working with persecuted Christians in Iraq since 2014 when Islamic State jihadists overran the province of Mosul, displacing tens of thousands of minority Christians and Yazidis.

It is principally active in the Iraqi Kurdish capital Arbil, where many Christians sought refuge.

The missing workers were in Baghdad "to renew their visas and register the association with Iraqi authorities," Blanchard said.

Before the US-led invasion of Iraq in 2003, Iraq's Christian population ran to an estimated 1.5 million.

By the summer of 2019, their number had fallen to around 250,000, Arbil Archbishop Bashar Warda said during a speech in Britain last year.