The mother and travelling companion of one of six victims of suspected methanol poisoning in Laos is demanding the UK government put the country on its travel no-go list.

Simone White, 28, a London lawyer, died along with two Australian backpackers, two Danes, and an American after becoming unwell while visiting the town of Vang Vieng – a popular stop on the backpacker trail through southeast Asia.

They were staying at the Nana Backpacker Hostel, which offered free shots of spirits thought to be tainted with methanol. The substance causes “coma, convulsions, blindness, nervous system damage and death,” according to the UK Health Security Agency.

Simone was travelling with her friend Bethany Clarke, who had met her in Asia after a stint working in Australia.

Bethany was also hospitalised but has recovered. Now, along with Simone’s mother, Sue White, she is campaigning for greater awareness of the risks of methanol poisoning – and for the Foreign Office to warn against travel to Laos.

Bethany told The Independent: “The UK should impose a ban on trips to Laos. The Lao authorities are failing to be honest and transparent about what’s happened.”

Were the Foreign Office to warn against travel to Laos, the effect would be to invalidate most travel insurance policies and put the nation off-limits to many British travellers.

The call follows reports that no action will be taken against 11 people arrested in connection with the mass poisoning.

Bethany said: “We found out that the 11 detainees were released without charge.

“One of the Danish fathers phoned me and said there’s been a big meeting – which we weren’t aware of – over in Laos, with the British ambassador, the Danish ambassador.

“He said: ‘Were you told the outcome?’

“I said I didn’t even know a meeting was taking place, but during the course of the conversation, I said ‘at least the 11 employees are still detained’.

“He said ‘no, they were released two weeks ago’. We’d never been told. We were given no updates at all.

“The Danish father that I spoke to said his understanding was the Lao government are very reluctant to pursue the investigation.

“They do literally want it swept under the carpet.

“The second thing that came out of the meeting was that they’re saying that it wasn’t a distillery problem. It did come from the hostel – the alcohol was tampered with at the hostel. So I don’t know why they let the employees go.”

Thavone Siharaj, deputy chief of the Lao Embassy in London, said that the government in Vientiane “immediately ordered investigations into the incident to identify the actual cause of the deaths and to ensure that perpetrators are brought to justice in accordance with the laws”.

He said the owner and staff of Nana Backpackers Hostel “have been released because there is not sufficient evidence to extend their detention according to the law”.

But he added: “They are committed to cooperate with the authorities and their passports are kept with the police as long as the investigation is not completed.”

A spokesperson for the Foreign, Commonwealth and Development Office said: ”We are supporting the family of a British woman who has died in Laos and we are in contact with the local authorities“

Last week the junior Foreign Office minister, Hamish Falconer, said in a written answer: “The risks of methanol poisoning are included in our travel advice pages where we see evidence of a trend that is likely to affect British nationals in that country or territory.

“We include information about the risks from methanol poisoning or counterfeit alcohol in our travel advice pages for Cambodia, Costa Rica, Fiji, Indonesia, Laos, Thailand, Turkey and Vietnam.

“In determining what we include in our travel advice, we assess a range of factors, including drawing on local knowledge and monitoring trends in consular cases.”

Sue White is hoping that politicians including Laura Trott, Conservative MP for Sevenoaks & Swanley, will add to the pressure on the Lao authorities.

“It’s just so difficult to kind of get any kind of justice,” she said.

Methanol poisoning occurs in a wide range of locations popular with travellers. The substance is tasteless and has only a faint smell, making it impossible to tell if a drink is contaminated.

Bethany Clarke and Sue White are also campaigning for funding to be organised for testing strips for travellers to detect whether methanol has been added to drinks.

At present there is no straightforward method to assess if the poison is present.