Exit statement from block results in error #6604

I have a simple block construct:

BLKF: block
  call fcn(x, f, flag)
  nf = nf + 1
  if (flag < 0) then
     exit BLKF
  end if
  phi = f**2
end block BLKF

Using Intel Parallel Studio XE 2015 for Windows, the following error is generated causing compilation to be aborted:

Error 1  error #6604: The CYCLE or EXIT statement must belong to a particular DO construct, and they do not.

Apparently, exit statements are not allowed in blocks. However, it was my understanding that it is one of the major benefits of using a block.

Any help will be greatly appreciated in this regard.

Best,

Avinash