grammatical number - Singular or plural verb after collective noun initialism

Are companies/groups of people considered plural? What about their initialisms?

I'm unsure if I should use have (plural verb) or has (singular) in the following situations:

The Federal Bureau of Investigation have developed a prototype ...

or

The Federal Bureau of Investigation has developed a prototype ...

and when using just the initialism:

The FBI have ...

or

The FBI has ...

If I'm referring to the FBI as a group of people, then I'd obviously go with have, whereas if it's an entity on it's own, then it'd be has.

Is there a preferred/recommended use in this case?

Answer

Recommendation:

The FBI have...

if you're writing/speaking British English, and

The FBI has...

if you're writing/speaking American English.

Yanks don't often think of companies/groups of people as collections of individuals, but Brits much more often do. That's my justification for my recommendation.

And if you're writing a formal paper, don't switch back and forth. Journal editors don't like it when you mix BrE and AmE idioms and spellings. They prefer consistency, if they care at all.