Can DNA paternity test samples be collected in different countries?

My family and I want a paternity test to be performed but we all live in different countries.

We want an official, government test (at a hospital) who can then issue a certificate of paternity robablility rather than a home test.

Can collect the samples at our diferent locations and send them in to the test centre, or do we have to be there in person?

Alos, I understand that the result will be more accurate with the mums DNA as well?

Cheers