Alexander Petrov and Ruslan Boshirov, who were formally accused of attempting to murder former Russian spy Sergei Skripal and his daughter Yulia in Salisbury, are seen on CCTV on Wilton Road in Salisbury on March 4, 2018 in an image handed out by the Metropolitan Police in London, Britain September 5, 2018. Metroplitan Police handout via REUTERS

LONDON (Reuters) - A nerve agent attack on a Russian former spy and his daughter in Salisbury, southern England, was probably a message to other Russians living overseas, British Prime Minister Theresa May said on Wednesday.

“I suspect that they wanted to give a message to those Russians who were living elsewhere who had been involved in matters relating to the Russian state,” May told parliament. “But it is up to the Russians to explain what happened in Salisbury.”