A hostel in Cardiff which bans British people from staying there is being investigated under race laws. Cardiff Backpackers, in the Riverside area of the city, advertises rooms on its website as available to "foreign passport holders only".
The Commission for Racial Equality (CRE) Wales has written to the hostel asking it to remove the advert.
Management said they did not discriminate and that they provided a sister hostel for British guests. The hostel, in Neville Street, is a short walk from the Millennium Stadium.
Hostel owner Sion Llewelyn did not want to comment but told the South Wales Echo that the rule was because he did not want unruly British guests spoiling the experience of foreign visitors. Mr Llewelyn added that he was not discriminating as British guests could use his sister hostel in a nearby street.
But Chris Myant, from CRE Wales, said the "foreign passport holders only" notice was illegal.
He said: "This is quite straightforwardly unlawful under the Race Relations Act, which says you must not advertise an intention to discriminate.
Cardiff Backpackers website screenshot
The hostel will only let foreign passport holders stay
"You can't put outside your house 'white purchasers only' or 'no black tenants' or anything like that. Direct racial discrimination on the grounds of nationality is unlawful and can't be justified."
The CRE has asked the hostel to declare that it will never advertise in that way again, and also for a justification of its stance. If the hostel refuses to change policy, Mr Myant said the CRE could take the case to court.
Bur Mr Myant acknowledged there could be reasons why such a restriction had been imposed which had nothing to do with racism. He added: "We would say to people, 'come to us and get proper advice.'
"We are not after punishing people because I think I can see some reasons why people running a hotel providing very cheap accommodation might want to restrict it to certain groups and that might have nothing to do with racial prejudice."
Hostel guest Bryce Stone, 30, said he had been staying at Cardiff Backpackers - despite being British.
Mr Stone, who has dual Australian-British nationality and speaks with an Australian accent, said: "They didn't ask me for my passport. It would not matter to me either way if there were British people staying there or whatever nationality."
But he admitted British backpackers had a reputation for being noisy. "They're notorious for being rowdy, but to be fair a lot of Australians who come here have that reputation as well - especially in London. It's just people getting away from their surroundings and letting their hair down," said Mr Stone, who has now settled in Cardiff from Adelaide. He added: "Backpackers is still the best hostel I've stayed in anywhere."