The United States will impose sanctions on Russia for its alleged use of a nerve gas agent in an attempt to poison former double agent Sergei Skripal and his daughter Yulia in England.

The US Department of State spokesperson Heather Nauert said it had been determined that Russia “has used chemical or biological weapons in violation of international law, or has used lethal chemical or biological weapons against its own nationals,” BBC reported.

The new sanctions will take effect on or around August 22, and relate to exports of electronic components and other technologies. The state department said “more draconian” sanctions will follow within three months if Russia does not give assurances that it will not use chemical weapons and allow on-site inspections by the United Nations.

On March 4, Skripal and his daughter were found unconscious on a park bench outside a shopping centre in Salisbury. They recovered after weeks of treatment.

The poisoning led to a major diplomatic controversy globally. The UK and its allies, including the European Union and the North Atlantic Treaty Organisation, accused Moscow of involvement in the incident and expelled 23 Russian diplomats from their territory. The US expelled 60 suspected Russian spies after the incident.

Russia has repeatedly denied claims that the nerve agent, Novichok, used to poison the pair was developed in the country or the Soviet Union.

In July, a woman died in Amesbury town in South West England after being exposed to the same nerve agent. Amesbury is about 12.87 km from Salisbury, the place where Skripal was poisoned.