Dynamic SQL Syntax help please

I created a simple function that i want to use another function (in the same schema) that will be used to create a sql statement. I get the following error when i try this:

ERROR:  syntax error at or near "EXEC" at character 1
QUERY:  EXEC SQL EXECUTE  $1  INTO  $2
CONTEXT:  SQL statement in PL/PgSQL function "fcn_population" near line 10

********** Error **********

ERROR: syntax error at or near "EXEC"
SQL state: 42601
Context: SQL statement in PL/PgSQL function "fcn_population" near line 10

Here is my function:

CREATE OR REPLACE FUNCTION fcn_population(p_date date, p_where varchar)
RETURNS numeric AS $$

DECLARE
    v_total_pop numeric := 0;
    v_stmt varchar(1024);
    v_where varchar(256) := 'where m.date_created < '||p_date||' '||+ integer '1'||' ';
                                 

BEGIN
    v_stmt := fcn_gen_statement(p_type, v_where, 0);
    EXEC SQL EXECUTE v_stmt INTO v_total_pop;
    return v_total_pop;
END;
$$ LANGUAGE plpgsql;