A councillor says Harrow has not done enough to engage with ethnic minorities to encourage them to foster or adopt.
Independent councillor Husain Akhtar says he raised the issue with officers at Harrow Borough Council at the end of last year.
And protests by the Somali community last week over the adoption of a child by a lesbian couple prompted him to draw attention to the problem again.
He said: “While Harrow Council might try to find matching foster carers and adopters, there is a case to improve the situation by creating and maximising same religion and culture fostering and adoption capacity within the communities concerned.
“This issue is much deeper than is being discussed. The council has not been doing enough to encourage different communities to register to foster or adopt.
“People who adopt a child can be single, married or unmarried; from any ethnic or religious background; heterosexual, lesbian, gay, bisexual or transgender.
“Therefore, even if the carer or adopter assures that the child could retain their birth religion, the impact of the environment in which the child grows is unavoidable.”
The Harrow Times has contacted the council about its fostering and adoption policy and is awaiting a reply.