Public health officials have reinforced warnings for people in Wiltshire to steer clear of any unidentified containers after the novichok victim Charlie Rowley claimed the nerve agent that left him critically ill was in a sealed and packaged perfume bottle.

Experts are urging residents and visitors not to pick up bottles or plastic and metal containers in Salisbury and Amesbury, and asked people to be wary of discarded cosmetics.

The mystery over the poisoning of Rowley and his partner, Dawn Sturgess, who died after being exposed to novichok, has deepened.

Rowley claimed Sturgess fell ill within 15 minutes after spraying what they believed was perfume on her wrists.

He claimed the substance was in a sealed bottle he found in a box wrapped in cellophane. Rowley said Sturgess recognised the brand and because it was sealed, boxed and looked expensive, they assumed it was safe.

However, Rowley, who was discharged from hospital at the end of last week, said he could not remember where he found the substance.

At a public meeting in Salisbury on Tuesday, Mike Wade of Public Health England, said: “It’s really important to stress that items such as plastic containers, small metal containers, glass containers should not be picked up. If you did not drop it, do not pick it up.

“It’s really important that those parents amongst us and those who look after young children as we enter the school holidays do reinforce that message. By suspicious items I’m talking about syringes, needles and cosmetics.”

During the same meeting, Paul Mills, the deputy chief constable of Wiltshire police, confirmed officers were still trying to pinpoint where Rowley found the novichok and whether there were any other sources of it.

Mills said counter-terrorism officers were working on the theory that the poisoning of Rowley and Sturgess at the end of last month was directly related to the attack on the former Russian spy Sergei Skripal and his daughter, Yulia, in March.

One theory has been that the Skripals’ attackers discarded the novichok they had used and this was found by Rowley and Sturgess.

But this could be undermined if Rowley is correct that the bottle he found was sealed and packaged, and makes the continuing scientific work to try to establish whether the novichok from the two incidents was from the same batch all the more crucial.

Rowley’s claims also raises the disturbing prospect of there being more undiscovered nerve agent in the area.

Work is nearing an end at two of the sites in Salisbury that were sealed off following the poisoning of Sturgess and Rowley. Sturgess’s home, a hostel called John Baker House, has been declared safe and is being returned to its owners.

Mills said a search of Queen Elizabeth Gardens in Salisbury is almost finished. Twenty-four specialist search officers have been combing the park, which Sturgess and Rowley visited the day before they fell ill.

They took away five industrial-sized bins of waste but found nothing of concern. Mills said the police did not have any specific intelligence about the park and the search was “highly precautionary”.

Speaking to ITV News, Rowley said he had a memory of Sturgess spraying the substance on her wrists at his home in Amesbury, eight miles north of Salisbury.

“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,” he said.

“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.

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