Russia accused Britain on Monday of refusing to allow access to Russian ex-spy Sergei Skripal and his daughter in violation of an international treaty, saying Moscow doesn't know whether they are alive or dead a year after they were reportedly attacked with a nerve agent.

Russia's deputy ambassador to the U.N., Dmitry Polyansky, said Britain is obligated to allow access under the Vienna Convention to determine whether the two are alive and want or need Moscow's help. Otherwise, he said, Britain could be responsible for "forced detention or even abduction of two Russian nationals."

Polyansky used the first anniversary of the attack in the city of Salisbury to again criticize Britain's refusal to provide proof for its allegation that Moscow was responsible for poisoning the Skripals with a nerve agent.

British Prime Minister Theresa May went to Salisbury on the anniversary to praise the "spirit and resolve" of its people after the attack, which left Sergei and Yulia Skripal in the hospital for weeks in critical condition. It also sickened a police officer and a man who came in contact with a perfume bottle containing traces of the nerve agent a few months later, and the man's girlfriend died.

The incident triggered a diplomatic freeze and raised tensions between the United Kingdom and Russia to their highest level since the Cold War. It led to the expulsion of more than 150 Russian diplomats by Britain, the U.S. and more than two dozen other allies — and to new sanctions against Russia.

Polyansky said that there has been no contact with the United Kingdom and that Russia hasn't responded to 10 pages of questions about the incident.

"It takes two to tango," he said. "We are ready to dance, no problem. We don't have a partner, since the very beginning."

Polyansky said the Russian government is worried about the fate of the Skripals and wants consular access to determine if they want help or not.

"The only way to determine it was to physically see the consul and say, 'Yes, we don't want your help,'" he said. "OK. We would be satisfied with this, but it wasn't done, in breach of the consular convention."

The British government said it does not comment on individual cases when asked about the Skripals' health. It noted that the Vienna Convention on consular access applies only to people who are "in prison, custody or detention" and the Skripals are not in detention.

A British diplomat, speaking on condition of anonymity because he was not authorized to speak publicly, said that the Skripals are alive and that they are "free citizens" who have requested privacy and do not want to meet anyone from the Russian Embassy.

Polyansky said repeatedly at the news conference that Britain and the rest of the world had determined Russia was responsible for masterminding the attack without proof.

He said Russia wants to keep a spotlight on its unanswered questions: How was the attack carried out? Who did it? And why was it done?

Polyansky asked rhetorically why Russia would want to kill Skripal, a former agent who was convicted of spying for Britain, when it had him in custody for eight years, why such "a strange method" was used, and why the government would carry out an attack just before presidential elections and hosting the World Cup.

"And if we tried to kill him, why didn't we kill him actually? Were these agents kind of newcomers? Interns? ... Why didn't they do it if they were asked to do it?" he added.

A year after the attack, Polyansky said, "We have a lot of unconfirmed things, even mysterious facts but no specifics and zero substance so far." Yet, Russia faces "international stigmatization" and its relations with Western countries have worsened, he said.

Britain's May said the poisoning was likely authorized at a senior level of the Russian state — a claim Moscow has repeatedly denied.

British police said two Russian military intelligence agents, travelling under aliases, went to Salisbury and used the Soviet-made nerve agent Novichok to poison Skripal and his daughter.

After Britain charged the two with trying to kill the Skripals, they appeared on Russian TV to deny any role in the attacks. Polyansky said they were not accused in Russia, and were "businessmen" living as "free people."

News from © The Associated Press, 2019