LONDON — The British police have identified suspects in the nerve agent attack on a former Russian spy and his daughter, and the suspects are believed to be in Russia, the newspaper The Daily Telegraph has reported, citing unnamed security officials.

Investigators have settled on “persons of interest” by scanning passengers on flights in and out of Britain, the newspaper reported. They have also gathered information from surveillance footage in the town of Salisbury, England, where the crime occurred, by zeroing in on car license plates.

A spokeswoman for the Metropolitan Police would not comment on the report, saying only that the police “are not discussing specific lines of inquiry.”