Yulia Skripal, who was poisoned along with former Russian spy Sergei Skripal last month, has rejected any help from the Russian embassy "at the moment".
It comes as the former intelligence officer's daughter was discharged from Salisbury District Hospital after recovering from novichok poisoning on Monday.
In a statement issued through the police, Skripal's daughter said she was not strong enough to give a media interview but "no-one speaks for me, or for my father."
After her release from the hospital, the Russian embassy in the UK tweeted that "they needed urgent proof that what was being done to her was on her free will".
Skripal's daughter, who was taken to a secure location, added: "I have specially trained officers available to me, who are helping to take care of me and to explain the investigative processes that are being undertaken."
"I have access to friends and family, and I have been made aware of my specific contacts at the Russian embassy who have kindly offered me their assistance in any way they can.
"At the moment I do not wish to avail myself of their services, but, if I change my mind I know how to contact them."
In response, London's Russian embassy said Yulia's comments were "an interesting read", but questioned whether they truly came from the 33-year-old.
"The text has been composed in a special way so as to support official statements made by British authorities," they said in a statement on their website.
The embassy queried what family the Skripals had been in contact with, besides Yulia’s cousin Victoria and Sergei's 90-year-old mother Elena Yakovlevna. Victoria Skripal, also Sergei's niece, has appeared on Russian media speculating over the nature of their attack and subsequent recovery.
The embassy's statement continued: "Particularly amazing is the phrase 'no one speaks for me' appearing in a statement which, instead of being read on camera by Yulia herself, is published at Scotland Yard website.
"To sum up, the document only strengthens suspicions that we are dealing with a forcible isolation of the Russian citizen."
Salisbury District Hospital has confirmed former Russian spy Sergei Skripal is making "good progress" and could be discharged "in due course".
The 66-year-old was found slumped beside his daughter Yulia on a bench in Salisbury, England, on March 4. It was later found that the pair had been poisoned by military-grade nerve agent novichok, which is thought to have been produced by Soviet scientists.
"Yulia has asked for privacy from the media and I would like to reiterate her request," said hospital director Christine Blanshard.
"Her father has also made good progress.
"Although he is recovering more slowly, we hope that he too will be able to leave hospital in due course."
Blanshard said the Skripals had received "round-the-clock care" and support from "world-leading experts" to aid their recovery. "Specialised decontaminated techniques" were also used to help them heal.
UK Prime Minister Theresa May laid blame on Moscow for the poisoning, telling Parliament last month that there was "no alternative conclusion other than that the Russian state was culpable".
Former military intelligence officer Sergei was arrested in Moscow on charges of treason in 2004 and jailed two years later, before being exchanged as part of a spy-swap deal with the US and relocated to Britain in 2010.
He remains in stable condition in hospital but was said to be "improving rapidly" late last week.