How could customer be controlled by blocking of despatch by country&regio

Hi Experts,

I have requirement in my project. The requirement has mentioned below:

Restrict availability by customer could be controlled by blocking despatch by country and region. How? How can block this country and region in the despatch?

What are the possible solutions available? pls explain me particular t.codes and customization settings .

It is treated as critical.

Thanks in adv.

Regards

Mohan