According to RT via CNN International, the pilots were told by Smolensk ATC to land in Minsk, but the pilots decided against it.
Reuters reporting the same.
http://www.reuters.com/article/idUSTRE6390NQ20100410?loomia_ow=t0:s0:a49:g43:r1:c0.798358:b32720734:z0
(snippet)
“..A Russian mission control official who had been present during conversations with the pilot told Reuters the pilot had ignored advice.
“The pilot was advised to fly to Moscow or Minsk because of heavy fog, but he still decided to land. No one should have been landing in that fog,” he said, on condition his name was not published.....”