libpq + utf-8

I met problems using libpq API with utf-8 database.
I can't figure out how to use, for example, function PQexec. This function has two parameters: PQexec(PGconn *conn,
constchar *command); 
If the command is, for example: INSERT INTO mytable (column1,column2,column3) VALUES ('non-English text 1','non-English
text2','non-English text 3') 
what format the string command[] should have? Should it be UTF-8, UTF-16 or ANSI(??) string?

When I use INSERT command with English data I can use ANSI string as command[] parameter and everything works fine, but
whenI try to INSERT, for example, Russian text into table columns, I fail using both UTF-8 and Windows1251 encoding in
command[].

 Sincerely, Konstantin S. Lokhtin, mailto:lokhtin@irkutsk.bnk.ru, ICQ: 233336237