The Equality and Human Rights Commission is to investigate gay-only hotels for possible breaches of equality law.
The body said it needed to establish an “objective balance” after investigating Christian-run hotels which bar gay couples.
Last month, a couple who own a hotel in Cornwall were ordered to pay £3,600 to a gay couple they refused a double room to.
The EHRC says it has not received any complaints over gay-only hotels but is looking for evidence of potential discrimination.
Two gay hotel owners told the Daily Telegraph that being forced to accept straight people would damage their businesses.
John Bellamy, who runs the gay-only Hamilton Hall in Bournemouth, said that equality legislation was a “double-edged sword” and claimed that forcing gay bars and hotels to accept straight people was killing gay culture.
Mark Hurst, a gay-only guesthouse owner from Brighton, said his customers felt more comfortable in gay-only atmospheres.
The EHRC said: “As discriminatory issues concerning ‘Christian’ bed and breakfast establishments and hotels have been officially brought to our attention, and as we are testing the law in this area, there is a need for the Commission to establish an ‘objective balance’.
“We are, therefore, looking in to the matter of ‘gay-only’ hotels’/B&B establishments and the potentially discriminatory policies towards heterosexual couples that some of those ‘gay-only’ establishments may hold.”
The EHRC funded the case against Christian hotel owners Peter and Hazelmary Bull.
A judge at Bristol crown court ruled that the Bulls had directly discriminated against civil partners Martin Hall and Stephen Preddy on the grounds of their sexual orientation.
Mr and Mrs Bull argued that they barred all unmarried couples from sharing rooms but the gay couple claimed that a straight couple could pretend to be married.
The Bulls are now set to appeal the ruling, with the financial backing of the Christian Institute.