Sales of Guatemala Babies

A United Nations envoy will visit Guatemala next week to investigate allegations of ''unscrupulous tactics'' in the sale of children to adoptive parents in the United States, Canada, France and Britain, the United Nations said today.

The envoy, Ofelia Calcetas-Santos, will look into the adoption trade in Guatemalan children during her trip from Monday to July 30, and then make recommendations to the Guatemalan Government.

A statement issued by the United Nations said concern had been raised by ''allegations of unscrupulous tactics used during the adoption process, as well as the large amounts of money paid by potential adoptive parents.''