MOSCOW (AP) — The gulf between Russia and Britain widened on Friday as they cranked up pressure over a nerve agent attack and a suspected murder in Britain that have deepened Western worries about alleged Russian meddling abroad.

Britain's foreign secretary accused Russian President Vladimir Putin of personally ordering the poisoning of ex-Russian spy Sergei Skripal and his daughter, Yulia, describing it as the most brazen such move since World War II.

Putin's spokesman denounced the claim as "shocking and inexcusable."

As relations between the two nations sank to a new post-Cold War low, near...