generate XML

Finally, I managed to automatically generate rather simple XML code. In R this is a matrix. The problem concerns how to write that matrix to file. I use write.table and the extension of file .xml Everything works perfect beside coding some language letters (Polish). But the problem disappears when I change the extension to .txt Therefore I write a file with .txt extension and after that I manually change the extension to .xml  - it does not solve the problem. Is it possible to write my matrix or txt file to valid xml file? I need to do it automatically.

Best,
Robert