How to query _entities in Apollo Router?

While resolving GraphQL request, Apollo Router makes requests that include field _entities(representations: $representations) to internal services.

However, when trying to issue the same query to externally available Apollo Router, I get an error

parsing error: cannot query field '_entities' on type 'Query'

So, internal service resolves _entities just fine, however Apollo Router return above error.

Is it possible to get Apollo Router resolve _entities without changing anything in Apollo Router?

If not, what can be changed in Apollo Router to resolve _entities?