The UK this week issued travel advice to tourists that warns of the dangers of visiting "anti-gay" U.S. states like North Carolina and Mississippi, both of which recently passed discriminatory legislation.

"The US is an extremely diverse society and attitudes towards LGBT people differ hugely across the country," the travel warning states. "LGBT travelers may be affected by legislation passed recently in the states of North Carolina and Mississippi. Before traveling please read our general travel advice for the LGBT community. You can find more detail on LGBT issues in the US on the website of the Human Rights Campaign," referring to the national equal rights advocacy group headquartered in Washington, D.C.

That group's director Ty Cobb said in response, "It is both frightening and embarrassing that one of our nation's staunchest allies has warned its citizens...of the risks of traveling to North Carolina and Mississippi because of anti-LGBT laws passed by their elected officials."

Mississippi Governor Phil Bryant earlier this month signed a controversial "religious freedom" law that critics say codifies LGBTQI discrimination, following a similar action by North Carolina Governor Pat McCrory, who in March approved a law that mandates transgender people use the bathrooms that correspond with their biological sex, rather than their gender identity, among other requirements.

In response, numerous state governments, businesses, advocacy groups, and music artists, among others, announced they would enact a boycott against the laws. New York City Mayor Bill de Blasio, for example, instituted a "non-essential" travel ban to North Carolina as part of what he called an expression of outrage growing throughout the country.

Now, it seems, that call has grown across the Atlantic.

According to the Greater Raleigh Convention and Visitors Bureau, which promotes tourism in the state of North Carolina, the various boycotts had already started to take effect prior to the UK's travel warning. The bureau said businesses in the state have already lost approximately $3.1 million.

Others who recently announced boycotts against the state are Pearl Jam, Ringo Starr, Bruce Springsteen, and Cirque du Soleil. North Carolina's HB2 law, otherwise known as the bathroom bill, "is a despicable piece of legislation that encourages discrimination against an entire group of American citizens," Pearl Jam wrote on the band's Facebook page.

Meanwhile, PayPal and other businesses have revoked plans to set up shop in the state.

"It is now more clear than ever that these terrible measures are not only harming individuals and taking an economic toll on the states, but are also causing serious damage to our nation’s reputation, and the perceived safety of LGBT people who travel here," Cobb said.

The North Carolina NAACP and Forward Together Moral Movement said they would host a "mass sit-in" against the bill on Monday, April 25, to protest what they call "every imaginable backward step of its far reaching acts of discrimination, homophobia, economic marginalization, and various threats of rights violations toward the LGBTQ community and others who faced a history of disenfranchisement."