SOFIA, March 26 (Xinhua) -- A total of 14 member states of the European Union (EU) have decided to expel Russian diplomats in response to the poisoning of a former Russian spy and his daughter in Britain, European Council President Donald Tusk announced Monday in Varna, Bulgaria.

Tusk told reporters that the European Council last week condemned in the strongest possible terms the recent attack in Salisbury, and the European Council agreed with the United Kingdom government's assessment that it is highly likely that the Russian Federation is responsible and that there is no plausible alternative explanation.

"As a direct follow up to last week's European Council decision to react to Russia within a common framework, already today 14 Member states have decided to expel Russian diplomats," Tusk said.

Additional measures, including further expulsions within this common EU framework are not to be excluded in the coming days and weeks, he added.

On March 4, former Russian intelligence officer Sergei Skripal and his daughter were found unconscious on a bench in a shopping center in the southern England city of Salisbury. They remain in a critical condition.

Britain claims they were exposed to a nerve agent and holds Russia responsible. The Russian Government has denied any involvement in the incident.

Following the incident, Britain expelled 23 Russian diplomats and announced freezing Russian state assets in Britain, suspension of all planned high-level bilateral contacts, and a boycott of this year's World Cup in Russia by ministers and royal family members. Moscow expelled an equal number of British diplomats in response.

Moscow insists on direct participation in the poisoning investigation.

"Russia firmly insists on a comprehensive investigation of what has happened in Salisbury. We are ready to take (a) most active part in it," Vladimir Yermakov, head of the Department for Nonproliferation and Arms Control at the Russian Foreign Ministry, said at a briefing for foreign diplomats.