BERN (Reuters) - Switzerland's main union federation said on Wednesday it would boycott talks the government has proposed on easing rules on wages and working conditions, a key element in talks on a new treaty with the European Union.
"The SGB (union federation) will not take part in the negotiations planned by (Economy Minister) Johann Schneider-Ammann on the flanking measures," it said in a statement.
Switzerland said last month it had put on hold further talks on future relations with the EU, including labour market rules, until after the summer break.
Negotiations to formalise ties now covered by around 100 separate accords have stumbled in recent weeks, with Swiss leaders conceding that Britain's planned exit from the EU has made it more difficult to clinch a deal.
Talks have snagged in particular on Switzerland's wish to protect its own labour market and pay and conditions for Swiss-based workers, a stance the government has in the past called a "red line" not up for negotiation.
"We will take all measures -- up to forcing a referendum -- to prevent a possible reduction of the protective measures," SGB President Paul Rechsteiner, a member of parliament for the centre-left Social Democrats party that is part of the governing coalition, told a news conference.
He said Schneider-Ammann's envisioned concessions went too far and would not win they support they need in the cabinet and parliament.
Rechsteiner in June had ruled out any weakening of laws to prevent foreign workers from undercutting local wages and working conditions, but his refusal on Wednesday to discuss any potential compromise takes the standoff to a new level.
(Reporting by Michael Shields; Editing by Catherine Evans)