create table as select block my insert (no replies)

Hi

i'm using mysql 5.5 and 5.6 on Amazon RDS and i'm trying to fugre out why my CREATE TABLE as SELECT block my queries.
I have a Master-Slave replication and I set the Slave to be in read/write mode.
then I issue this statement:
CREATE TABLE ofir as SELECT * FROM SOME_TABLE;

then I have noticed that the replication lag started to raise, so I run the following query and found that my CREATE TABLE is blocking the insert from the sql slave thread.
SELECT * FROM information_schema.INNODB_TRX;
results:
trx_id...........trx_state......trx_query
------------------------------------------
234557D6E.....LOCK WAIT....INSERT INTO `some_table`
2345554D4.....RUNNING......create table ofir as select * from


SELECT * FROM information_schema.INNODB_LOCKS;

lock_id................................lock_trx_id.......lock_mode......lock_type
-------------------------------------------------------------------------------
234557D6E:85:885976:13...234557D6E......X,GAP.......RECORD
2345554D4:85:885976:13...2345554D4......S..............RECORD


I have tried different isolation levels:
"set transaction isolation level read committed;"
and also "read uncommited" , but still I had replication lag growing and same table lock.
does anyone have the same problem or know how to avoid it ?

I have read about "innodb_locks_unsafe_for_binlog" but in 5.6 documentation it say it is deprecated so I don't want to use it.


Thanks,
Ofir