They said the woman hailing from Moradabad in Uttar Pradesh, was found carrying the rounds yesterday evening by CISF personnel at the Adarsh Nagar station when her bag was being scanned.
The lady was travelling with her father and other family members, they said adding her father produced a copy of his arms license and said the 20 rounds of ammunition (.32 calibre) belongs to him.
Security in the Delhi Metro and other public transport facilities is stepped up in view of the Republic day celebrations on January 26.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.