By Jon Leyne
BBC correspondent in Baghdad
The British company that provides security to the airport, Global, has withdrawn its services in what it says is a contractual dispute.
Military flights, however, are not affected.
Travelling out of Baghdad airport is hazardous enough at the best of times but now it is not possible at all, at least on civilian flights.
It is understood that Global has not been paid by the Iraqi government for three months.
It is not clear whether there is any connection but the Iraqi transport ministry is frequently accused of corruption.
A former transport minister is wanted for questioning over the issue.
The Iraqi government is also notoriously unreliable about paying its own employees.
When the airport is open, several airlines provide commercial flights inside Iraq and to several neighbouring countries.
Because of the threat of missiles, planes execute a corkscrew manoeuvre on landing and take-off.
At last, real progress in the effort to totally corrupt Iraqi society. The NeoCons must be really proud.