UK's May says response to Skripal attack hurt Russian spying

British Prime Minister Theresa May says the West's response to the nerve-agent poisoning of a former spy has seriously hurt Russia's intelligence capability.

May's office says she'll urge countries "to stand up for the rules around the world" during a foreign-policy speech on Monday.

Britain accuses Russia of poisoning ex-spy Sergei Skripal and his daughter with a Soviet-made nerve agent in the English city of Salisbury in March a claim Moscow denies.

After the attack Britain and other countries expelled a total of 150 Russian spies working under diplomatic cover. Russia expelled a similar number of those countries' envoys.

May plans to tell the Lord Mayor's Banquet in London that this was "the largest-ever collective expulsion of Russian intelligence officers, fundamentally degrading Russian intelligence capability for years to come.