ZURICH (Reuters) - A referendum in Switzerland to clarify the country s relationship with the European Union would be helpful, Swiss President Doris Leuthard said on Sunday, after ties between the two sides cooled this week. Switzerland s frictions with the EU, of which it is not a member, arise as Britain negotiates its withdrawal from the bloc following a referendum in June last year and seeks a new trading relationship with its closest neighbors. Talks on securing a new  framework  treaty to govern the Swiss-EU relationship have been underway for some time, with Brussels wanting to replace the more than 100 bilateral accords which regulate its relationship with Bern. But relations soured this week when the EU granted Swiss stock exchanges only limited access to the bloc, prompting Swiss threats of retaliation for what it called discrimination.  The bilateral path is important,  Leuthard told Swiss newspapers Sonntags Blick.  We therefore have to clarify our relationship with Europe. We have to know in which direction to go.  Therefore a fundamental referendum would be helpful.  Talks on the an all-encompassing agreement made headway last month after Switzerland agreed to increase its contribution to the EU s budget. Such a deal would ensure Switzerland adopts relevant EU laws in return for enhanced access to the bloc s single market, crucial for Swiss exports. But a deal would be opposed by the anti-EU Swiss People s Party (SVP), currently the biggest group in parliament.  Leuthard, who steps down as president at the end of the year, said the latest row had not overshadowed her year in the rotating office.  Of course, the differences with Brussels are now in focus. Here our attitude is clear - for the EU to link such a technical thing like stock exchange equivalency with a political question like the framework treaty, that is not possible,   She said some countries were putting Switzerland in the same category as Britain, while others wanted to strengthen their own financial centers at Switzerland s expense.  Others think we are cherry pickers who benefit too much from the single European market, they want to increase pressure for a framework agreement,  Leuthard said. Pressure from outside would did not contribute to a beneficial climate in Switzerland over a potential agreement, she said. She said she understood Swiss scepticism towards the EU, but there was no alternative to finding an accommodation with the bloc which generates around two thirds of Swiss trade.  We can strengthen the cooperation with India and China, but the EU remains central. We need a mechanism and regulated relationship with the EU, that would also prevent political games like we are having at the moment,  Leuthard said. 