Release letter for changing my company

Dear all,

I request all of you to give me a proper advice for the below subject.

I am currently working in one of the government organization for almost 2 years.before i was working with one private entity and got release letter(visa got tranferred)from them for my present employer.

Now i got a good offer from another goverment organization
and planning to move.

so in this case , will i get the release letter from my present employer(govt) to the new one.bcoz i recently heard about the new rule that release letter will not be issued from one govermt organization to another govt organization.
Is it true ? if yes, how can i proceed to change from my present employer to new employer.

Thanks in advance for your valuable response.