LONDON — British prime minister Theresa May says former spy Sergei Skripal and his daughter may never recover from a nerve-agent attack that has left them in critical condition.

May says “their condition is unlikely to change in the near future, and they may never recover fully.”

May told lawmakers that more than 130 people in the English city of Salisbury may have been exposed to the nerve agent used to poison the Skripals. More than 50 people have been assessed in hospitals.

A police officer left seriously ill after the March 4 attack was released from hospital last week.

The U.K. blames Russia for the attack, but Moscow denies responsibility. On Monday about 20 countries, including the United States, joined Britain in expelling Russian diplomats in response to the poisoning.