Nerve agent used on ex-spy

LONDON — A former Russian spy and his daughter were poisoned by a nerve agent in Britain this week, British police said Wednesday, heightening suspicions that the episode was an assassination attempt, perhaps by Russia.

The development forces the British government to confront the possibility that, once again, an attack on British soil was carried out by the government of President Vladimir Putin, which Western intelligence officials say has ordered the killing of people who have crossed it.

Prime Minister Theresa May, Cabinet ministers and the government’s emergency security committee discussed the matter Wednesday.

“This is being treated as a major incident involving attempted murder by administration of a nerve agent,” said Mark Rowley, chief police official for counterterrorism and international security.

Sergei Skripal, 66, and his daughter, Yulia Skripal, 33, “were targeted specifically,” Rowley said. He refused to say what chemical was used.

In 2006, a Russian court convicted Skripal, a former colonel in Russia’s military intelligence, of selling secrets to the British. In 2010, he was released and sent to Britain in an exchange of imprisoned spies.

Sunday afternoon, he and his daughter became ill in Salisbury, England, where Sergei Skripal lives. Both lost consciousness and remain in critical condition.

Some of the responders who went to the scene also became ill, with one police officer in serious condition, Rowley said.

The Kremlin has denied involvement.