New Delhi, Aug 21 - At least 20 flights were delayed and 10 diverted in the national capital Friday evening following torrential rains that also damaged a portion of the new domestic terminal building.

'Heavy downpour resulted in some water entering into the domestic terminal building 1D. The maintenance team is working on war footing to clear the water and restore the displaced sheets,' the Delhi International Airport Ltd (DIAL), the developer of the IGI airport, said in a statement.

'Flight operations are on and we are hoping to clear the backlog in the next couple of hours,' it added.

An airport official said no one was injured when a portion of the new terminal building roof collapsed.

Heavy rains lashed the capital from around 2.30 p.m. and within an hour there was disorder on the streets with reports of waterlogging and resultant traffic snarls on several arterial roads. The downpour finally ended around 5.15 p.m.