A £50 charge on blessings for same-sex couples has been called a gay tax.
Brighton and Hove City Council has been accused of discriminating against gay couples after announcing the price increase.
Although the commitment ceremonies are also open to heterosexual couples, so far it has only been same-sex couples who have opted for the service - an alternative to a wedding.
The charge means couples who wish to have their relationship officially recognised will now have to pay £155 instead of the £97.50 charged for official marriage ceremonies.
Green councillor Simon Williams said the 50 per cent increase would hit the gay community hardest as it was the only ceremony available to gay couples, who can not get married legally.
Of the 60 couples who have opted for the ceremony since it was introduced in November 2002, about 50 per cent have been gay men and the rest lesbians.
Coun Williams said: "It's basically going to be a tax on gay couples.
"The council knows it's the only way gay, lesbian and bisexual people can get official recognition of their relationships. It adds insult to injury."
Coun Williams, who is thinking of having a commitment ceremony with his male partner, said announcing the increase as many couples celebrated Valentine's Day was insensitive.
Phil Barber, 41, and his partner Steve Hullock, 30, are planning a commitment ceremony. They have bought the rings but are now reconsidering having it in Brighton.
Mr Barber, a sales director, said: "It strikes me as discrimination when the gay community has no other option. It seems unfair and wrong.
"If the government believes £97.50 is the right price for a marriage ceremony, why should commitment ceremonies be any different?
"They're cashing in on the fact Brighton has a high gay population and more and more people are choosing to have ceremonies."
At the moment gay couples have no legal rights. Mr Barber hopes the Government's pending Relationships Bill will change this.
He said: "It's about time we had the same rights as straight couples, for example the right to visit our partners in hospital."
A city council spokesman said: "We hope it's not an attempt to paint the council as homophobic.
"Given the diverse sexuality of our councillors, staff and managers that would be a little strange. The council is promoting Stonewall's campaign for gay partnership rights.
"The price of commitment ceremonies is the same for gay and straight.
"By definition that is not discriminatory.
"Romance might be dead but no straight couple is going to choose marriage because it's cheaper. They are utterly separate markets.
"The marriage fee is set nationally and we cannot increase it. The fact that only heterosexual people can get married is a separate issue outside the council's control."
The council has also put up the price of baby naming and vow renewal ceremonies from £150 to £155.
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