PRAGUE, Czech Republic - Dozens of Czech firms and the local branches of foreign companies including Coca-Cola, Ikea and Microsoft called on the prime minister on Wednesday to press for passage of legislation enabling same-sex marriages.

The EU member of 10.5 million people allowed registered partnerships for gay couples in 2006, but such unions lack many of the same rights given to married people.

A bill that would allow same-sex marriages was approved in a first reading in parliament in June.

But the bill's future is uncertain as lawmakers across the political divide voted against it, including the majority of right-wing, conservative Civic Democrats of Prime Minister Petr Fiala.

Opponents, including some Civic Democrats, are also pushing for a constitutional amendment defining marriage only as a relationship between a man and a woman.

"In the 21st century, we cannot have a situation wherein people are not equal before the law," said Petr Dvorak, the chief executive of mobile operator Vodafone CZ, who initiated the open letter signed by 66 firms and published on Wednesday.

"The current situation concerning the rights of LGBT+ people is absolutely not in line with western-style democracy," Dvorak wrote on the Vodafone website.

The signatories also include the Czech branches of Deloitte, IBM, Mastercard and T-Mobile, local banks, food producers and other companies such automaker Skoda.

They said the inequality has a negative impact on the Czech economy, citing an analysis by the Open For Business initiative.

Discrimination worsens the financial situation of LGBT+ people as it prevents them from working in some cases, the companies warned.

A law enabling same-sex marriages would help keep the gay workforce in the country and could attract new skilled workers from abroad, the appeal said.

"Discrimination in general results in a lower productivity of minority groups including LGBT+ people," said Vojtech Bartos, an economist at the University of Milan.

In a poll conducted by the Czech Academy of Sciences in March-May this year, 58 percent of respondents were in favour of same-sex marriages while 38 percent were against.