Most Czechs back eurosceptic President Vaclas Klaus's demands for an opt out from the Lisbon Treaty as the price for signing the much-delayed EU text, but the prime minister said his actions were damaging the country, Reuters reported. Klaus stunned the Czech government and other EU members last week by demanding Czechs be granted an opt-out that would prevent property claims by ethnic Germans expelled from the country after World War Two. The president is the only EU leader not to have signed in to law a treaty which aims to streamline decision-making in the 27-member bloc and give it more clout on the world stage. His defiance has complicated efforts to ensure the treaty comes into force in January, as other EU countries want. Klaus has struck a chord with voters in the Czech Republic, where anxiety over the post-war expulsion of the 3 million Sudeten Germans still surfaces from time to time. A poll by the Median agency showed 65 percent of Czechs backed Klaus as they feared laws expelling Germans after the war could be circumvented. Three quarters said Klaus should not resign if he fails to sign the treaty. Families of the expelled Germans have demanded that the Czechs recognise it was wrong to use the principle of collective guilt in expelling the Germans. Many of the Germans supported Hitler's Germany, which annexed the German-populated areas of Czechoslovakia under the Munich agreement in 1938. Prime Minister Jan Fischer told business leaders at a conference on Friday that Klaus's last-minute demand was seriously harming the republic. "It is a very damaging matter, very harmful for the Czech Republic, let's admit this to ourselves," Fischer said. "Member states could be reasonably offended, this is not primarily a matter for the Czech Republic," he said. Both houses of parliament have approved the treaty and the government has been negotiating with Klaus on his demands. It said it would try to negotiate on the issue with EU partners if Klaus pledged to sign the treaty afterwards. Klaus has so far made no such pledge. Most lawyers and the government say Klaus's concerns are unfounded and analysts say Klaus, who has long been a fierce opponent of the treaty, is just being obstructive.