Finding context for error log

I get the following message in my postgres log:

ERROR:  42601: syntax error at or near "%" at character 269
LOCATION:  yyerror, scan.l:761

I have a fairly complex schema (lots of database objects) and many users 
hitting the db with lots of connections, so I'm not really sure what bit 
of code is causing the problem.  Is there an easy way to get postgres to 
spit out the SQL statement it was parsing when it generated the error?

I've experimented with log_error_verbosity and log_min_messages but 
still haven't seen any SQL in the log.

Kyle