Britain on Thursday said that the poison Novichok used to attack a former spy and his daughter was manufactured by Russia. "Novichok, which is a military grade nerve agent, cannot be manufactured by a non-state sponsor. It was identified by our world leading experts of defence science and technology departments," British High Commissioner to India Dominique Asquith told the media here. According to him, there were "two plausible explanationsa of the attack - "either a direct act by Russia against Britain or the (Russian) government lost control of the military grade nerve agents'. Former Russian spy who became a double agent for Britain, Sergei V. Skripal, 66, and his daughter Yulia, 33, were found collapsed after being poisoned last week. Both remain in a serious condition along with a police officer who came in contact with the same substance. Skripal, who is a retired Russian military intelligence officer, was jailed for 13 years by Russia in 2006 for spying for Britain. In retaliation to the incident, British Prime Minister Theresa May on Wednesday expelled 23 Russian diplomats. The reaction came from Britain after Russia denied any involvement in the attempted murder. "The 23 expelled diplomats have been identified as under-clad intelligence officers," Asquith said. "We provided the Russian government an opportunity to respond and their denial clearly demonstrated total disdain. They did not give any explanation how the agent came to be used in Britain." The High Commissioner said that Britain will consider whether more measures were necessary as the investigation continues. "We took some action as we were entitled to. We have our own weapon convention act and we followed that," he added. Meanwhile, Russian Foreign Minister Sergei Lavrov in an interview to news agency Sputnik on Wednesday said that Russia would also expel Britain diplomats "soon".