British Prime Minister Theresa May has urged Iran’s president to resolve the case of a British-Iranian woman who faces trial on security-related charges.

May’s office says she spoke by telephone Tuesday to President Hassan Rouhani and “raised concerns” about Nazanin Zaghari-Ratcliffe and other dual nationals. It says May “stressed the importance of resolving these cases as we worked to strengthen our diplomatic relationship.”

Charity worker Zaghari-Ratcliffe was detained in April while trying to fly out of Iran with her toddler daughter. She has been accused of planning the “soft toppling” of the government and faces trial on unspecified charges.

Iran and Britain have been rebuilding their diplomatic relationship since reopening their respective embassies last year, shortly after Tehran and world powers struck a deal on Iran’s contested nuclear program.