The mayor of Philadelphia, who is a strong supporter of equal marriage, has been accused of discrimination for saying he will not officiate at same-sex weddings until after a court challenge to the legality of licencing such weddings has been resolved.

A spokesman for Mayor Michael Nutter made the announcement on Monday. It was met with disappointment by a Philadelphia gay couple who asked the mayor to oversee their wedding after they obtained their marriage licence in Montgomery County.

The administration of Governor Tom Corbett, and the Pennsylvania health department are suing D Bruce Hanes, a county clerk who has issued over a hundred marriage licences to same-sex couples, defying a state ban on equal marriage, because he said he thought it was unconstitutional.

D Bruce Hanes, the register of wills in Montgomery County in southeast Pennsylvania previously said he wants to come down “on the right side of history and the law”, as he originally agreed to issue a licence to two women who contacted him in July.

“It’s discrimination,” said Marcus Saitschenko, 52, who wants to marry Jim Goldstein, his partner of 22 years. The couple obtained their licence from Hanes. “I’m asking the mayor to do the right thing.”

The director of the city’s LGBT Affairs Office, Gloria Casarez, denied the accusation of discrimination, saying that the request “had not been denied”. She said, rather, that the city wants to be sure that marriages performed there, “are on firm legal ground”.

A spokesman for Nutter, Mark McDonald, said the request for him to marry the couple was the same as asking him to break the state’s 1996 Marriage Law, which specifically defines marriage as between one man and one woman.

McDonald said Nutter supports the American Civil Liberties Union’s legal challenge to the law, but the ACLU said McDonald is taking “a fraught position”, on the issue.