The director of Amnesty International in Ireland has said the Civil Partnership Bill published last month treats gay and lesbian people as second class citizens.
Speaking at the Belfast Pride week, Colm O' Gorman said the failure of the legislation to provide for the children of same-sex couples was a cowardly decision by the Government.
Civil partnerships were officially recognised in Northern Ireland and Britain four years ago.
An Irish Human Rights Commission report suggested the lack of similar legislation in the Republic could be in breach of the Good Friday Agreement.
The Government set up a working group and last month the Minister for Justice Dermot Ahern published the Civil Partnership Bill.
He said it gave people in same-sex relationships many of the rights of married couples and could not go further without breaching the Constitution.
However, Mr O' Gorman believes the Bill enshrines discrimination against gay people into Irish law.
Meanwhile, the BT Group has been praised for its recognition of diversity.
It has been named the most 'gay friendly' firm in the world after years of providing same-sex partner benefits for its staff.