Koirala, who is on a visit to the national capital, met Singh at his residence. In a statement issued by BJP, the party said Singh raised the issue of increasing number of religious conversion of poor Nepali Hindus through allurement.
"He also expressed BJP's concern over news reports of changes made in Nepal's Hindu charter although 90 per cent of the Nepali population is Hindu," the party said.
"It is for the people of Nepal to decide who shall govern them. But peaceful and progressive Nepal is in India's best interest," Singh said.
Koirala apprised Singh of the current political situation in Nepal and reaffirmed his party's commitment for early elections in Nepal.
BJP Overseas Affairs Global Convener Vijay Jolly and party spokesman Sudhanshu Trivedi were among those present on the occasion.