TEHRAN — Britain’s foreign secretary, Boris Johnson, expressed concern on Saturday in Tehran about British-Iranian citizens detained in Iran, a group that includes Nazanin Zaghari-Ratcliffe, whose trial and imprisonment has stirred tensions between the two nations.

Mr. Johnson, who was accused of worsening Ms. Zaghari-Ratcliffe’s situation with remarks earlier this year, met with Foreign Minister Mohammad Javad Zarif during his first visit to the region as foreign secretary. They were to discuss a number of issues, including Britain’s debt to the Iranian government, the Iran nuclear agreement and the conflict in Yemen, which has spawned one of the world’s worst humanitarian crises.

Before the trip, Mr. Johnson said in a statement that he would also “stress my grave concerns about our dual national consular cases and press for their release where there are humanitarian grounds to do so.” The British Foreign Office said later on Saturday that Mr. Johnson “had a constructive meeting” with Mr. Zarif that included discussion of the cases.

Ms. Zaghari-Ratcliffe, 38, an employee of the Thomson Reuters Foundation, the independent charitable arm of the news agency, was arrested in 2016 while she and her daughter, a toddler, were visiting family in Iran. Ms. Zaghari-Ratcliffe was sentenced to a five-year prison term on charges of plotting to overthrow Iran’s government.