Russia has accused the UK of casting a veil over the case of poisoned spy Sergei Skripal, claiming he is being held against his will.
Mr Skripal and his daughter were poisoned with a nerve agent in Salisbury in March, and have since declined offers of help from their home country of Russia.
But Russian foreign ministry spokeswoman Maria Zakharova says the Skripals are being held in Britain against their will and has claimed the former spy Mr Skripal is still a Russian citizen, despite finding refuge in the UK when he was found to be a double agent.
She said: "We see it as a murder attempt of Russian citizens and huge political provocations and burden of proof lies with UK side. They still refuse to provide consular access saying Yulia does not want to communicate with any Russian representatives while Sergei is a national of UK.
"We would like to see proof that they're refusing and we haven't seen that so far," she added.
"We want to hear them say it to us out loud if they don't want any contact.
"We see it as a forceful containment, that they're being taken by UK state – gross violation of bilateral agreements."
She also said that Britain is continuing to point the finger at Russia without evidence about who was behind the attempted murder of the father and daughter.
She added that Russia will be doing all it can to "disentangle the situation" so the process "will be more transparent so the veil cast by UK will be lifted".
Speaking at a weekly media briefing, Ms Zakharova also commented on Viktoria Skripal, the cousin of Yulia, and her failed attempts to be granted a visa.
She said: "Not long ago they refused to give Viktoria Skripal a visa, they said if she requests a visa again this will be considered.
"But again this is nothing but a lie – Viktoria was refused on a second application without any explanation at all. [It] Completely contradicts statements made by UK government."
Last week, the country's ambassador to the UK, Alexander Yakovenko, repeated his claim that Britain had "abducted" the pair as they recovered from the novichok poison attack in Salisbury.
Parts of the cathedral city were cordoned off for weeks as police conducted the investigation, and there have been warnings that "hot spots" of the poison could remain.
They were targeted with up to 100mg of the deadly nerve agent, with the highest concentration of it found on Mr Skripal's front door.
The UK's representative to the United Nations, Karen Pierce, told a meeting in April there was "no plausible alternative explanation than Russian state responsibility for what happened in Salisbury".
She said: "Russia has a proven record of conducting state-sponsored assassinations including on the territory of the United Kingdom.
"No terrorist group or non-state actor would be able to produce this agent in the purity described by the OPCW testing and this is something Russia has acknowledged.
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"The Russian state has previously produced novichok and would still be capable of doing so today."
Mr Skripal and his daughter have defied medical odds – he is no longer in a critical condition and she has been discharged from hospital.