UNICEF executive director Ann Veneman told reporters at the end of a three-day official visit on Saturday that her organization "was concerned by high levels of HIV infection in the country."
"We are working with the ministry of the interior in dealing with uncontrolled immigration of Zimbabwean women who are engaged in sexual activities in central Mozambique."
She did not give details of the organization's work with the government.
Large numbers of women are believed to have fled poverty-stricken Zimbabwe, laboring under the world's highest inflation rate and major food shortages, to work as prostitutes in neighboring Mozambique.
According to government figures, Mozambique's HIV prevalence rate among the 16-to-49 age group is estimated at more than 16 percent. However some aid groups say the figure is higher.