cut and append the file based on id

Hi,

I have a file which have set of rows and has to create separate files based on the id.

Eg:
001_AHaris020
001_ATony030
002_AChris090
002_ASmit060
003_AJhon001

Output: I want three files like 001_A.txt, 002_A.txt and 003_A.txt.

001_A.txt should have

 Haris020
 Tony030

002_A.txt should have

 Chris090
 Smit060

003_A.txt should have

  Jhon001

Please give some ideas using cut command having in the while loop...

Double post. Continued here.