WARSAW, June 27 (Reuters) - Poland posted a budget deficit of 20.85 billion zlotys ($5.15 billion) at the end of May, the finance ministry said on Tuesday.

At the end of April, the budget deficit had stood at 10 billion zlotys.

($1 = 4.0487 zlotys) (Reporting by Anna Wlodarczak-Semczuk, editing by Jason Hovet)