The U.S. will impose sanctions on Russia over the poisoning of a Russian agent and his daughter on UK soil, the State Department announced Wednesday.

Sergei and Yulia Skripal were poisoned by a nerve agent in March in the southern English city of Salisbury. The British government has blamed the incident on Russia, linking the nerve agent to a series of Russia-developed chemical weapons collectively known as Novichok.

The Kremlin has denied responsibility.

The Skripals have since recovered from the alleged assassination attempt.

In announcing the forthcoming penalties, the State Department said it determined Moscow "used chemical or biological weapons in violation of international law or has used lethal chemical or biological weapons against its own nationals."

The department cited the decades-old Chemical and Biological Weapons Control and Warfare Elimination Act, which was passed in 1991.

The sanctions are expected to take effect on or around Aug. 22 following a congressional notification period.

At least two other people were hospitalized after suffering from exposure to Novichok in a town near Salisbury.

Charlie Rowley, 45, was released from a hospital last month, but his partner, Dawn Sturgess, 44, died after exposure.

Rowley and Sturgess were hospitalized after being exposed to the deadly nerve agent June 30. Police found a bottle containing the substance at the scene. Sturgess succumbed to the poisoning and passed away in hospital.