Can you please tell me whether an Uzbekistan passport holder, traveling to Australia, with a 12-hour stopover in Delhi airport, India, requires a transit visa? Even if they are staying inside the airport?
As stated in Timatic, the database used by airlines:
TWOV (Transit Without Visa): Holders of confirmed onward tickets for a max. transit time of 24 hours
So if your trip is in a single booking, you do not need a visa