How much time does MNC company normally take to give an offer letter?

Hi all, I attended an interview on Dec 2nd 2014 and cleared all rounds in the interview process. I forwarded my photo, All educations documents to HR on 3rd of Dec and after that there was a long UAE National holiday period till 7th of Dec. In the second week I sent a couple of follow up Emails to HR but there was no reply. I sent one more follow up email in the 3rd week and received a auto reply email stating " I am out of office till 1 week. you can contact XXX HR for any escalations" Hence, I sent a follow up Email to XXX HR. XXX HR has checked my profile history and replied back with this message "Some internal Clearances are going on,will revert to you accordingly" Does any one have the idea why this much delay to release the offer? How much time does MNC company normally take to give an offer letter? Are they really releasing the offer? What are the internal clearances? Thanks, Subbu