David Cameron has hit out at laws rolling back anti-discrimination protection in two US states which have been branded "anti-gay" by campaigners.
The Foreign Office has warned that lesbian, gay, bisexual and transgender (LGBT) people could be "affected" by the legislation passed in North Carolina and Mississippi.
Speaking alongside US president Barack Obama, the Prime Minister said laws should be used to end discrimination "rather than to embed it".
The official travel advice issued by the Foreign Office said: "The US is an extremely diverse society and attitudes towards LGBT people differ hugely across the country. LGBT travellers may be affected by legislation passed recently in the states of North Carolina and Mississippi."
At a joint press conference with the US president in the Foreign Office, Mr Cameron said: "I have been to North Carolina, many years ago, and enjoyed it. I have not yet made it to Mississippi but one day I hope to.
"The guidance we have put out - the Foreign Office gives advice on travel and it obviously deals with laws and situations as they are and it tries to give that advice dispassionately and impartially and it is very important that it does so.
"It's something that a lot of attention is given to.
"Our view on any of these things is that we believe we should be trying to use law to end discrimination rather than to embed it or enhance it and that's something we are comfortable saying to countries and friends anywhere in the world.
"But obviously the laws people pass is a matter for their own legislatures but we make clear our own views about the importance of trying to end discrimination and we have made some important steps forward in our own country on that front, which we are proud of."
Rock stars including Bruce Springsteen and former Beatle Ringo Starr have cancelled performances in North Carolina in protest at the law passed by the state, while Bryan Adams pulled out of a gig in Mississippi.
Mr Obama said the law in North Carolina should be overturned but said Americans in that state and Mississippi are "wonderful people" and that British citizens would be treated with "extraordinary hospitality".