The transport department's move comes after the Supreme Court directed the government in this regard.
"All Motor Licensing Officer (MLOs) have been directed to start granting NOCs to owners of over 10-year-old diesel vehicles, so that they could sell them to buyers outside Delhi-NCR," the official said.
In April last year, the National Green Tribunal had banned all diesel vehicles which are more than 10 years old.
Noting that diesel is a prime source of air pollution in Delhi, the green body had said, "a number of countries like Brazil, China, Denmark etc are in the process or have prohibited diesel vehicles are, in the process of doing away with them and imposing stringent taxes on the vehicles.
Later, the Supreme Court had also dismissed the plea challenging the Tribunal's order.