A Swiss right-wing political party has agreed to either change or remove advertising posters which call gay couples infertile.

The Swiss People’s Party (UDC) is campaigning against a proposal to extend tax benefits to same-sex partners.

The party’s general secretary added to the controversy by telling Leman Bleu TV that gay people contribute nothing to society because they do not have children.

A spokesman denied the UDC is homophobic.

A referendum will be held on 20th May on the proposal to allow same-sex couples to be exempt from inheritance tax if when one of them dies.

“We have made a mistake in communications,” said UDC deputy Yves Nidegger told Tribune de Genève newspaper.

“The term ‘infertile’ was badly chosen. We regret having offended anyone.”

Opposition parties have criticised the ad campaign, and gay activists are meeting today to prepare their response.

Switzerland passed legislation to recognise same-sex partnerships in 2004, and it came into effect on January 1st 2007.

Same-sex civil unions, which were approved by a country-wide referendum in 2005, do not grant full marital rights to gay and lesbian couples.

The unions have a similar legal status, but gay couples are barred from adopting children or from receiving IVF treatment.

The referendum was the first time in Europe that the issue of same sex partnerships had been the subject of a plebiscite.

The partnership legislation was passed by the Council of States and the National Council in 2004.

Due to Switzerland’s unique system of ‘direct democracy,’ Swiss citizens who collect 50,000 signatures in 30 days can force a referendum on any new law.

The Roman Catholic Church were instrumental in forcing a referendum on same-sex unions, but in the event 60% of Swiss voted for the new law.

The Protestant Churches supported the legislation.