can salary details be released

Some time yes

I have never come across a company in my over two decades of working life which has tried to ask another company for salary details of an applicant. Possibly, this will also hold true in your case.

Generally they cannot ask for your salary earnings from your old employer. They may ask you what you are expecting to get in your new job so they can try to match it or come close to it if they think you are worthy.

for what reason???