The British man poisoned with the nerve agent novichok has claimed the substance that killed his girlfriend and left him critically ill came in a bottle disguised as a legitimate perfume in a sealed box.

Charlie Rowley claimed his partner, mother-of-three Dawn Sturgess, fell ill within 15 minutes of spraying the bottle, which he said he had found, on to her wrists at his home in Amesbury, Wiltshire.

In his first interview since he was discharged from hospital, Rowley told ITV News: “I do have a memory of her spraying it on her wrists and rubbing them together.

“I guess that’s how she applied it and became ill. I guess how I got in contact with it is when I put the spray part to the bottle ... I ended up tipping some on my hands but I washed it off under the tap.

“It was an oily substance and I smelled it and it didn’t smell of perfume. It felt oily. I washed it off and I didn’t think anything of it. It all happened so quick.

“Within 15 minutes, Dawn said she had a headache. She asked me if I had any headache tablets. In that time she said she felt peculiar and needed to lie down in the bath. I went into the bathroom and found her in the bath, fully clothed, in a very ill state.”

Counter-terrorism detectives are working on the theory that the poisoning of Rowley and Sturgess at the end of last month is directly linked to the poisoning of the Russian spy Sergei Skripal and his daughter, Yulia, in Salisbury in March.

Experts from the top secret research facility at Porton Down in Wiltshire are trying to establish if the novichok was from the same batch.

But if Rowley is correct about the perfume bottle being boxed and sealed, it may undermine the line of inquiry that the novichok that he and Sturgess came into contact with had been discarded by the attackers of the Skripals.

It also opens up the possibility that there may yet be more novichok that has not been found in Wiltshire.

Rowley said he had found a sealed box in a cellophane wrapper containing a perfume bottle some days before he and Sturgess fell ill, and had kept it at his home in Amesbury, eight miles north of Salisbury, before handing it to his partner of two years as a gift.

He said he was struggling to remember where he had originally found the item but was convinced it was legitimate, as it looked like it hadn’t been used, “Which made me think it was quite safe,” he said.

Rowley also said it was a perfume that Sturgess recognised. “It’s very strange. It’s quite scary to think that something can be disguised in that manner and left to be found in public.

“It looked expensive, unfortunately it turned out to be a bad find.”

He added: “I’ve lost so much. I feel very sad about what happened to her; it’s awful and shocking. I was still on medication when they told me she passed away. I don’t think I will ever be able to get over it.”

He felt the burden of responsibility, but attacked whoever left the bottle of novichok lying around in public. “I think it was very irresponsible for people to leave the poison for anybody to pick up. It could have been children. It was just so unfortunate. I’m very angry at the whole incident,” he said.

Rowley’s revelations prompted concern at a public meeting in Salisbury to discuss the poisonings on Tuesday evening.

Paul Mills, deputy chief constable of Wiltshire police, said it was “critical” to find out if the novichok was from the same batch. He said: “The investigation is focused on how, when and where Charlie and Dawn came into possession of the bottle.

“Searches are continuing at various locations as officers look to identify other potential sites or sources of contamination.”

He refused to speak in detail about Rowley’s claims. “We’re aware Mr Rowley has decided to conduct an interview as is his right. This is a multifaceted investigation. It’s very sensitive and the counter-terrorism network has been clear from day one that we’re not going to conduct an ongoing dialogue in relation to the investigation as it would be inappropriate to do so.”

Mills confirmed that police still believed the Skripals came into contact with the novichok that they were poisoned with on Skripal’s front door handle.

Rowley’s claims led the leader of Wiltshire council, Lady Scott, to repeat the warning that people should not pick up items. “If you haven’t dropped it then don’t pick it up,” she said.