By Jan Lopatka and Alicja Ptak PRAGUE/WARSAW (Reuters) – Officials in Central Europe voiced concern on Sunday that they were reaching capacity to comfortably house some of the nearly 3.5 million refugees who have fled Ukraine since Russia’s invasion and are now camped in temporary accommodation. Most of the Ukrainians have arrived at border points in Poland, Slovakia, Romania and Hungary, data compiled by the U.N. refugee agency shows, putting pressure on the European Union countries now attempting to shelter them. Czech Interior Minister Vit Rakusan said the government would seek to extend a …