Should I Join A Company Without Receiving The Offer Letter

Hi,
On may 25th I attended the walk in interview that was going in IBM for the position of HR recruiter. I cleared 3 rounds and was asked to leave for the day.
Next day I got a call from them and told me that I got selected and the location that they were offering is hyderabad. I accepted their offer.
On June 1st I submitted my documents to them.
Today is June 10th and till now I haven't received any confirmation / offer letter from their end. They are pressuring me to join by next week.
Kindly help me. Should I join them before receiving the Offer Letter or not.
Thanks

Hi. Sir I'm pradeep. I'm have done sap mm. Ps and sd module....... But till now.. I'm not getting job.... So please request to help me... My contact number 9551795196

Joining a company without their formal appointment letter / offer letter is not good and can be dangerous with some companies. (I am not referring to any particular employer.)
ASB